Oracle Database 2 Day Developer's Guide, 11g Release 2 (11.2)

11g Release 2 (11.2)

E10766-04

Contents

List of Examples

List of Tables

Title and Copyright Information

Preface

- Audience

- Documentation Accessibility

- Related Documents

- Conventions

1 Introduction

- About Oracle Database Developers

- About This Document

- About Oracle Database

- About Schema Objects

- About Oracle Database Access

- About SQL*Plus

- About SQL Developer

- About Structured Query Language (SQL)

- About Procedural Language/SQL (PL/SQL)

- About Other Client Programs, Languages, and Development Tools

- About Sample Schema HR

2 Connecting to Oracle Database

- Connecting to Oracle Database from SQL*Plus

- Connecting to Oracle Database from SQL Developer

- Connecting to Oracle Database as User HR

- Unlocking the HR Account

- Connecting to Oracle Database as User HR from SQL*Plus

- Connecting to Oracle Database as User HR from SQL Developer

3 Exploring Oracle Database with SQL Developer

- Tutorial: Viewing HR Schema Objects

- Tutorial: Viewing EMPLOYEES Table Properties and Data

4 Selecting Table Data

- About Queries

- Running Queries in SQL Developer

- Tutorial: Selecting All Columns of a Table

- Tutorial: Selecting Specific Columns of a Table

- Displaying Selected Columns Under New Headings

- Selecting Data that Satisfies Specified Conditions

- Specifying Conditions with Regular Expressions

- Sorting Selected Data

- Selecting Data from Multiple Tables

- Using Operators and Functions in Queries

- Using Arithmetic Operators in Queries

- Using Numeric Functions in Queries

- Using the Concatenation Operator in Queries

- Using Character Functions in Queries

- Using Datetime Functions in Queries

- Using Conversion Functions in Queries

- Using Aggregate Functions in Queries

- Using NULL-Related Functions in Queries

- Using CASE Expressions in Queries

- Using the DECODE Function in Queries

5 About DML Statements and Transactions

- About Data Manipulation Language (DML) Statements

- About the INSERT Statement

- About the UPDATE Statement

- About the DELETE Statement

- About Transaction Control Statements

- Committing Transactions

- Rolling Back Transactions

- Setting Savepoints in Transactions

6 Creating and Managing Schema Objects

- About Data Definition Language (DDL) Statements

- About Schema Object Names

- Creating and Managing Tables

- About SQL Data Types

- Creating Tables

- Tutorial: Creating a Table with the Create Table Tool

- Creating Tables with the CREATE TABLE Statement

- Ensuring Data Integrity in Tables

- About Constraint Types

- Tutorial: Adding Constraints to Existing Tables

- Tutorial: Adding Rows to Tables with the Insert Row Tool

- Tutorial: Changing Data in Tables in the Data Pane

- Tutorial: Deleting Rows from Tables with the Delete Selected Row(s) Tool

- Managing Indexes

- Tutorial: Adding an Index with the Create Index Tool

- Tutorial: Changing an Index with the Edit Index Tool

- Tutorial: Dropping an Index

- Dropping Tables

- Creating and Managing Views

- Creating Views

- Tutorial: Creating a View with the Create View Tool

- Creating Views with the CREATE VIEW Statement

- Tutorial: Changing Views with the Edit View and Rename Tools

- Dropping Views

- Creating and Managing Sequences

- Tutorial: Creating a Sequence

- Dropping Sequences

- Creating and Managing Synonyms

- Creating Synonyms

- Dropping Synonyms

7 Developing Stored Subprograms and Packages

- About Stored Subprograms

- About Packages

- About PL/SQL Identifiers

- About PL/SQL Data Types

- Creating and Managing Standalone Stored Subprograms

- About Subprogram Structure

- Tutorial: Creating a Standalone Stored Procedure

- Tutorial: Creating a Standalone Stored Function

- Changing Standalone Stored Subprograms

- Tutorial: Testing a Standalone Stored Function

- Dropping Standalone Stored Subprograms

- Creating and Managing Packages

- About Package Structure

- Tutorial: Creating a Package Specification

- Tutorial: Changing a Package Specification

- Tutorial: Creating a Package Body

- Dropping a Package

- Declaring and Assigning Values to Variables and Constants

- Tutorial: Declaring Variables and Constants in a Subprogram

- Ensuring that Variables, Constants, and Parameters Have Correct Data Types

- Tutorial: Changing Declarations to Use the %TYPE Attribute

- Assigning Values to Variables

- Assigning Values to Variables with the Assignment Operator

- Assigning Values to Variables with the SELECT INTO Statement

- Controlling Program Flow

- About Control Statements

- Using the IF Statement

- Using the CASE Statement

- Using the FOR LOOP Statement

- Using the WHILE LOOP Statement

- Using the Basic LOOP and EXIT WHEN Statements

- Using Records and Cursors

- About Records

- Tutorial: Declaring a RECORD Type

- Tutorial: Creating and Invoking a Subprogram with a Record Parameter

- About Cursors

- Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

- Tutorial: Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

- About Cursor Variables

- Using a Cursor Variable to Retrieve Result Set Rows One at a Time

- Tutorial: Using a Cursor Variable to Retrieve Result Set Rows One at a Time

- Using Associative Arrays

- About Collections

- About Associative Arrays

- Declaring Associative Arrays

- Populating Associative Arrays

- Traversing Dense Associative Arrays

- Traversing Sparse Associative Arrays

- Handling Exceptions (Run-Time Errors)

- About Exceptions and Exception Handlers

- Handling Predefined Exceptions

- Declaring and Handling User-Defined Exceptions

8 Using Triggers

- About Triggers

- Creating Triggers

- About OLD and NEW Pseudorecords

- Tutorial: Creating a Trigger that Logs Table Changes

- Tutorial: Creating a Trigger that Generates a Primary Key for a Row Before It Is Inserted

- Creating an INSTEAD OF Trigger

- Creating Triggers that Log LOGON and LOGOFF Events

- Changing Triggers

- Disabling and Enabling Triggers

- About Trigger Compilation and Dependencies

- Dropping Triggers

9 Working in a Global Environment

- About Globalization Support Features

- About Language Support

- About Territory Support

- About Date and Time Formats

- About Calendar Formats

- About Numeric and Monetary Formats

- About Linguistic Sorting and String Searching

- About Length Semantics

- About Unicode and SQL National Character Data Types

- About Initial NLS Parameter Values

- Viewing NLS Parameter Values

- Changing NLS Parameter Values

- Changing NLS Parameter Values for All SQL Developer Connections

- Changing NLS Parameter Values for the Current SQL Function Invocation

- About Individual NLS Parameters

- About Locale and the NLS_LANG Parameter

- About the NLS_LANGUAGE Parameter

- About the NLS_TERRITORY Parameter

- About the NLS_DATE_FORMAT Parameter

- About the NLS_DATE_LANGUAGE Parameter

- About NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT Parameters

- About the NLS_CALENDAR Parameter

- About the NLS_NUMERIC_CHARACTERS Parameter

- About the NLS_CURRENCY Parameter

- About the NLS_ISO_CURRENCY Parameter

- About the NLS_DUAL_CURRENCY Parameter

- About the NLS_SORT Parameter

- About the NLS_COMP Parameter

- About the NLS_LENGTH_SEMANTICS Parameter

- Using Unicode in Globalized Applications

- Representing Unicode String Literals in SQL and PL/SQL

- Avoiding Data Loss During Character-Set Conversion

10 Deploying an Oracle Database Application

- About Deployment Environments

- About Installation Script Files

- About DDL Statements and Schema Object Dependencies

- About INSERT Statements and Constraints

- Creating Installation Script Files

- Creating an Installation Script File with SQL Developer

- Editing Installation Script Files that Create Sequences

- Editing Installation Script Files that Create Triggers

- Tutorial: Creating an Installation Script File for the Sequence and Tables

- Tutorial: Creating an Installation Script File for the Package

- Tutorial: Creating an Installation Script File for the Synonym and View

- Tutorial: Creating an Installation Script File for the Data

- Installing the Sample Application

- Checking the Validity of an Installation

- Archiving the Installation Script Files

Index

List of Examples

- 2-1 Connecting to Oracle Database from SQL*Plus

- 4-1 Displaying Selected Columns Under New Headings

- 4-2 Preserving Case and Including Spaces in Column Aliases

- 4-3 Selecting Data from One Department

- 4-4 Selecting Data from Specified Departments

- 4-5 Selecting Data for Last Names that Start with the Same Substring

- 4-6 Selecting Data for Last Names that Include the Same Substring

- 4-7 Selecting Data that Satisfies Two Conditions

- 4-8 Selecting All Managers in the EMPLOYEES Table

- 4-9 Selecting All Employees Whose Last Names Have Double Vowels

- 4-10 Displaying Phone Numbers in a Different Format

- 4-11 Extracting the Street Number from Each STREET_ADDRESS

- 4-12 Counting the Number of Spaces in Each STREET_ADDRESS

- 4-13 Reporting the Position of the First Space in Each STREET_ADDRESS

- 4-14 Sorting Selected Data by LAST_NAME

- 4-15 Sorting Selected Data by an Unselected Column

- 4-16 Selecting Data from Two Tables (Joining Two Tables)

- 4-17 Using an Arithmetic Expression in a Query

- 4-18 Rounding Numeric Data

- 4-19 Truncating Numeric Data

- 4-20 Concatenating Character Data

- 4-21 Changing the Case of Character Data

- 4-22 Trimming Character Data

- 4-23 Padding Character Data

- 4-24 Extracting Substrings from Character Data

- 4-25 Replacing Substrings in Character Data

- 4-26 Displaying the Number of Months Between Dates

- 4-27 Displaying the Number of Years Between Dates

- 4-28 Displaying the Last Day of a Selected Month

- 4-29 Displaying a Date Six Months from a Selected Date

- 4-30 Displaying System Date and Time

- 4-31 Converting Dates to Characters Using a Format Template

- 4-32 Converting Dates to Characters Using Standard Formats

- 4-33 Converting Numbers to Characters Using a Format Template

- 4-34 Converting Characters to Numbers

- 4-35 Converting a Character String to a Date

- 4-36 Converting a Character String to a Time Stamp

- 4-37 Counting the Number of Rows in Each Group

- 4-38 Counting the Number of Distinct Values in a Set

- 4-39 Using Aggregate Functions for Statistical Information

- 4-40 Limiting Aggregate Functions to Rows that Satisfy a Condition

- 4-41 Showing the Rank and Percentile of a Number Within a Group

- 4-42 Showing the Dense Rank of a Number Within a Group

- 4-43 Substituting a String for a NULL Value

- 4-44 Specifying Different Expressions for NULL and Not NULL Values

- 4-45 Using a CASE Expression in a Query

- 4-46 Using the DECODE Function in a Query

- 5-1 Using the INSERT Statement When All Information Is Available

- 5-2 Using the INSERT Statement When Not All Information Is Available

- 5-3 Using the INSERT Statement Incorrectly

- 5-4 Using the UPDATE Statement to Add Data

- 5-5 Using the UPDATE Statement to Update Multiple Rows

- 5-6 Using the DELETE Statement

- 5-7 Committing a Transaction

- 5-8 Rolling Back an Entire Transaction

- 5-9 Rolling Back a Transaction to a Savepoint

- 6-1 Creating the EVALUATIONS Table with CREATE TABLE

- 6-2 Creating the SCORES Table with CREATE TABLE

- 6-3 Creating the EMP_LOCATIONS View with CREATE VIEW

- 7-1 Assigning Values to a Variable with Assignment Operator

- 7-2 Assigning Table Values to Variables with SELECT INTO

- 7-3 Inserting a Table Row with Values from Another Table

- 7-4 IF Statement that Determines Return Value of Function

- 7-5 CASE Statement that Determines Which String to Print

- 7-6 FOR LOOP Statement that Computes Salary After Five Years

- 7-7 WHILE LOOP Statement that Computes Salary to Maximum

- 7-8 Using the EXIT WHEN Statement

- 7-9 Declaring Associative Arrays

- 7-10 Populating Associative Arrays

- 7-11 Traversing a Dense Associative Array

- 7-12 Traversing a Sparse Associative Array

- 7-13 Handling Predefined Exception NO_DATA_FOUND

- 7-14 Handling User-Defined Exceptions

- 8-1 Creating an INSTEAD OF Trigger

- 9-1 NLS_LANGUAGE Affects Server Message and Month Abbreviations

- 9-2 NLS_TERRITORY Affects Currency Symbol

- 9-3 NLS_TERRITORY Affects Date Formats

- 9-4 NLS_DATE_FORMAT Overrides NLS_TERRITORY

- 9-5 NLS_DATE_LANGUAGE Affects Displayed SYSDATE

- 9-6 NLS_CALENDAR Affects Displayed SYSDATE

- 9-7 NLS_NUMERIC_CHARACTERS Affects Decimal Character and Group Separator

- 9-8 NLS_CURRENCY Overrides NLS_TERRITORY

- 9-9 NLS_ISO_CURRENCY

- 9-10 NLS_SORT Affects Linguistic Sort Order

- 9-11 NLS_COMP Affects SQL Character Comparison

- 9-12 NLS_LENGTH_SEMANTICS Affects Storage of VARCHAR2 Column

List of Tables

- 7-1 Cursor Attribute Values

- 9-1 Initial Values of NLS Parameters in SQL Developer

Oracle® Database

2 Day Developer's Guide

11g Release 2 (11.2)

E10766-04

June 2010

Oracle Database 2 Day Developer's Guide, 11g Release 2 (11.2)

E10766-04

Copyright © 2008, 2010, Oracle and/or its affiliates. All rights reserved.

Primary Author:  Sheila Moore

Contributors: Pat Huey, Sharon Kennedy, Simon Law, Roza Leyderman, Bryn Llewellen, Chuck Murray, Mark Townsend

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The information contained herein is subject to change without notice and is not warranted to be error-free. If you find any errors, please report them to us in writing.

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Preface

This document explains basic concepts behind application development with Oracle Database. It provides instructions for using the basic features of topics through Structured Query Language (SQL), and the Oracle server-based procedural extension to the SQL database language, Procedural Language/Structured Query Language (PL/SQL).

Preface topics:

- Audience

- Documentation Accessibility

- Related Documents

- Conventions

Audience

This document is intended for anyone who is interested in learning about Oracle Database application development, and is primarily an introduction to application development for developers who are new to Oracle Database.

This document assumes that you have a general understanding of relational database concepts and an understanding of the operating system environment that you will use to develop applications with Oracle Database.

Documentation Accessibility

Our goal is to make Oracle products, services, and supporting documentation accessible to all users, including users that are disabled. To that end, our documentation includes features that make information available to users of assistive technology. This documentation is available in HTML format, and contains markup to facilitate access by the disabled community. Accessibility standards will continue to evolve over time, and Oracle is actively engaged with other market-leading technology vendors to address technical obstacles so that our documentation can be accessible to all of our customers. For more information, visit the Oracle Accessibility Program Web site at http://www.oracle.com/accessibility/.

Accessibility of Code Examples in Documentation

Screen readers may not always correctly read the code examples in this document. The conventions for writing code require that closing braces should appear on an otherwise empty line; however, some screen readers may not always read a line of text that consists solely of a bracket or brace.

Accessibility of Links to External Web Sites in Documentation

This documentation may contain links to Web sites of other companies or organizations that Oracle does not own or control. Oracle neither evaluates nor makes any representations regarding the accessibility of these Web sites.

Access to Oracle Support

Oracle customers have access to electronic support through My Oracle Support. For information, visit http://www.oracle.com/support/contact.html or visit http://www.oracle.com/accessibility/support.html if you are hearing impaired.

Related Documents

As you become comfortable with the concepts and tasks in this document, Oracle recommends that you consult other Oracle Database development documents, especially:

- Oracle Database 2 Day + Application Express Developer's Guide

- Oracle Database 2 Day + Java Developer's Guide

- Oracle Database 2 Day + .NET Developer's Guide

- Oracle Database 2 Day + PHP Developer's Guide

For more information, see:

- Oracle Database Advanced Application Developer's Guide

- Oracle Database Concepts

- Oracle Database SQL Language Reference

- Oracle Database PL/SQL Language Reference

Conventions

This document uses these text conventions:

Convention

Meaning

boldface

Boldface type indicates graphical user interface elements associated with an action, or terms defined in text or the glossary.

italic

Italic type indicates book titles, emphasis, or placeholder variables for which you supply particular values.

monospace

Monospace type indicates commands within a paragraph, URLs, code in examples, text that appears on the screen, or text that you enter.

1 Introduction

This chapter contains the following topics:

- About Oracle Database Developers

- About This Document

- About Oracle Database

- About Sample Schema HR

About Oracle Database Developers

An Oracle Database developer is responsible for creating or maintaining the database components of an application that uses the Oracle technology stack. Oracle Database developers either develop applications or convert existing applications to run in the Oracle Database environment.

See Also:

Oracle Database Concepts for more information about the duties of Oracle Database developers

About This Document

This document is the entry into the Oracle Database documentation set for application developers. It does the following:

- Explains the basic concepts behind development with Oracle Database

- Shows how to use basic features of SQL and PL/SQL

- Provides references to detailed information about subjects that it introduces

- Shows, with tutorials and examples, how to develop and deploy a sample application

Chapter 1, "Introduction," describes the reader for whom this document is intended, outlines the organization of this document, introduces important Oracle Database concepts, and describes the sample schema used in the tutorials and examples in this document.

Chapter 2, "Connecting to Oracle Database," explains how to connect to Oracle Database.

Chapter 3, "Exploring Oracle Database with SQL Developer," shows how to view schema objects and the properties and data of Oracle Database tables.

Chapter 4, "Selecting Table Data," shows how to use queries to retrieve data from an Oracle Database table.

Chapter 5, "About DML Statements and Transactions," introduces data manipulation language (DML) statements and transactions. DML statements add, change, and delete Oracle Database table data. A transaction is a sequence of one or more SQL statements that Oracle Database treats as a unit: either all of the statements are performed, or none of them are.

Chapter 6, "Creating and Managing Schema Objects," introduces data definition language (DDL) statements, which create, change, and drop schema objects. The tutorials and examples show how to create the objects for the sample application.

Chapter 7, "Developing Stored Subprograms and Packages," introduces stored subprograms and packages, which can be used as building blocks for many different database applications. The tutorials and examples show how to create the package of subprograms for the sample application.

Chapter 8, "Using Triggers," introduces triggers, which are stored PL/SQL units that automatically execute ("fire") in response to specified events. The tutorials and examples show how to create the triggers for the sample application.

Chapter 9, "Working in a Global Environment," introduces globalization support—National Language Support (NLS) parameters and Unicode-related features of SQL and PL/SQL.

Chapter 10, "Deploying an Oracle Database Application," explains how to deploy a database application—that is, how to install it in one or more environments where other users can run it—using the sample application as an example.

About Oracle Database

Oracle Database groups related information into logical structures called schemas. The logical structures are called schema objects. When you connect to the database by providing your user name and password, you specify the schema and indicate that you are its owner. In Oracle Database, the user name and the name of the schema to which the user connects are the same.

Topics:

- About Schema Objects

- About Oracle Database Access

About Schema Objects

Every object in an Oracle Database belongs to only one schema, and has a unique name with that schema.

Some of the objects that schemas can contain are:

- Tables
Tables are the basic units of data storage in Oracle Database. Tables hold all user-accessible data. Each table contains rows that represent individual data records. Rows are composed of columns that represent the fields of the records. For more information, see "Creating and Managing Tables".

- Indexes
Indexes are optional objects that can improve the performance of data retrieval from tables. Indexes are created on one or more columns of a table, and are automatically maintained in the database. For more information, see "Managing Indexes".

- Views
You can create a view that combines information from several different tables into a single presentation. A view can rely on information from both tables and other views. For more information, see "Creating and Managing Views".

- Sequences
When all records of a table must be distinct, you can use a sequence to generate a serial list of unique integers for numeric columns, each of which represents the ID of one record. For more information, see "Creating and Managing Sequences".

- Synonyms
Synonyms are aliases for schema objects. You can use synonyms for security and convenience; for example, to hide the ownership of an object or to simplify SQL statements. For more information, see "Creating and Managing Synonyms".

- Stored subprograms
Stored subprograms (also called schema-level subprograms) are procedures and functions that are stored in the database. They can be invoked from client applications that access the database. For more information, see "Developing Stored Subprograms and Packages".

Triggers are stored subprograms that are automatically run by the database when specified events occur in a particular table or view. Triggers can restrict access to specific data and perform logging. For more information, see "Using Triggers".

- Packages
A package is a group of related subprograms, along with the explicit cursors and variables they use, stored in the database as a unit, for continued use. Like stored subprograms, package subprograms can be invoked from client applications that access the database. For more information, see "Developing Stored Subprograms and Packages".

Typically, the objects that an application uses belong to the same schema.

See Also:

Oracle Database Concepts for a comprehensive introduction to schema objects

About Oracle Database Access

You can access Oracle Database only through a client program, such as SQL*Plus or SQL Developer. The client program's interface to Oracle Database is Structured Query Language (SQL). Oracle provides an extension to SQL called Procedural Language/SQL (PL/SQL).

Topics:

- About SQL*Plus

- About SQL Developer

- About Structured Query Language (SQL)

- About Procedural Language/SQL (PL/SQL)

- About Other Client Programs, Languages, and Development Tools

About SQL*Plus

SQL*Plus (pronounced sequel plus) is an interactive and batch query tool that is installed with every Oracle Database installation. It has a command-line user interface that acts as the client when connecting to the database.

SQL*Plus has its own commands and environment. In the SQL*Plus environment, you can enter and run SQL*Plus commands, SQL statements, PL/SQL statements, and operating system commands to perform tasks such as:

- Formatting, performing calculations on, storing, and printing query results

- Examining tables and object definitions

- Developing and running batch scripts

- Performing database administration

You can use SQL*Plus to generate reports interactively, to generate reports as batch processes, and to output the results to text file, to screen, or to HTML file for browsing on the Internet. You can generate reports dynamically using the HTML output facility.

You can use SQL*Plus in SQL Developer. For details, see Oracle Database SQL Developer User's Guide.

See Also:

- "Connecting to Oracle Database from SQL*Plus"

- SQL*Plus User's Guide and Reference for complete information about SQL*Plus

About SQL Developer

SQL Developer (pronounced sequel developer) is a graphic version of SQL*Plus, written in Java, that is available in the default installation of Oracle Database and by free download.

The SQL Developer user interface includes a navigation frame, tools (with menus), and a SQL Worksheet. From the SQL Worksheet, you can enter and run SQL statements, PL/SQL statements, and SQL*Plus commands. You can do some tasks—for example, creating a table—either in the SQL Worksheet or with the navigation frame and tools.

To see the name and keyboard equivalent of any SQL Developer icon, position your cursor over the icon.

See Also:

- "Connecting to Oracle Database from SQL Developer"

- Oracle Database SQL Developer User's Guide for complete information about SQL Developer

About Structured Query Language (SQL)

Structured Query Language (SQL) (pronounced sequel) is the set-based, high-level computer language with which all programs and users access data in Oracle Database.

SQL is a declarative, or nonprocedural, language; that is, it describes what to do, but not how. You specify the desired result set (for example, the names of current employees), but not how to get it.

See Also:

- Oracle Database Concepts for a complete overview of SQL

- Oracle Database SQL Language Reference for complete information about SQL

About Procedural Language/SQL (PL/SQL)

Procedural Language/SQL (PL/SQL) (pronounced P L sequel) is a native Oracle Database extension to SQL. It bridges the gap between declarative and imperative program control by adding procedural elements, such as conditional control and loops.

In PL/SQL, you can declare constants and variables, procedures and functions, types and variables of those types, and triggers. You can handle exceptions (run-time errors). You can create PL/SQL units—procedures, functions, packages, types, and triggers—that are stored in the database for reuse by applications that use any of the Oracle Database programmatic interfaces.

The basic unit of a PL/SQL source program is the block, which groups related declarations and statements. A block has an optional declarative part, a required executable part, and an optional exception-handling part.

See Also:

- Oracle Database Concepts for a complete overview of PL/SQL

- Oracle Database PL/SQL Language Reference for complete information about PL/SQL

About Other Client Programs, Languages, and Development Tools

Some other database access clients, languages, and tools that you can use to develop applications are:

Topics:

- Oracle Application Express (APEX)

- Oracle Java Database Connectivity (JDBC)

- Hypertext Preprocessor (PHP)

- Oracle Call Interface (OCI)

- Oracle C++ Call Interface (OCCI)

- Open Database Connectivity (ODBC)

- Pro*C/C++ Precompiler

- Pro*COBOL Precompiler

- Microsoft .NET Framework

- Oracle Provider for OLE DB (OraOLEDB)

- Oracle Objects for OLE (OO4O)

See Also:

- Oracle Database Concepts for more information about tools for Oracle Database developers

- Oracle Database Advanced Application Developer's Guide for information about choosing a programming environment

Oracle Application Express (APEX)

Oracle Application Express (APEX) is an application development and deployment tool that enables you to quickly create secure and scalable Web applications even if you have limited previous programming experience. The embedded Application Builder tool assembles an HTML interface or a complete application that uses schema objects, such as tables or stored procedures, into a collection of pages that are linked through tabs, buttons, or hypertext links.

See Also:

Oracle Database 2 Day + Application Express Developer's Guide for more information about APEX

Oracle Java Database Connectivity (JDBC)

Oracle Java Database Connectivity (JDBC) is an API that enables Java to send SQL statements to an object-relational database, such as Oracle Database. Oracle Database JDBC provides complete support for the JDBC 3.0 and JDBC RowSet (JSR-114) standards, advanced connection caching for both XA and non-XA connections, exposure of SQL and PL/SQL data types to Java, and fast SQL data access.

See Also:

For more information about JDBC:

- Oracle Database Concepts

- Oracle Database Advanced Application Developer's Guide

- Oracle Database 2 Day + Java Developer's Guide

Hypertext Preprocessor (PHP)

The Hypertext Preprocessor (PHP) is a powerful interpreted server-side scripting language for quick Web application development. PHP is an open source language that is distributed under a BSD-style license. PHP is designed for embedding database access requests directly into HTML pages.

See Also:

Oracle Database 2 Day + PHP Developer's Guide for more information about PHP

Oracle Call Interface (OCI)

Oracle Call Interface (OCI) is the native C language API for accessing Oracle Database directly from C applications.

The OCI Software Development Kit is also installed as part of the Oracle Instant Client, which enables you to run applications without installing the standard Oracle client or having an ORACLE_HOME. Your applications work without change, using significantly less disk space.

See Also:

- Oracle Database Advanced Application Developer's Guide for more information about OCI

- Oracle Call Interface Programmer's Guide for complete information about OCI

Oracle C++ Call Interface (OCCI)

Oracle C++ Call Interface (OCCI) is the native C++ language API for accessing Oracle Database directly from C++ applications. Very similar to the OCI, OCCI supports both relational and object-oriented programming paradigms.

The OCCI Software Development Kit is also installed as part of the Oracle Instant Client, which enables you to run applications without installing the standard Oracle client or having an ORACLE_HOME. Your applications work without change, using significantly less disk space.

See Also:

- Oracle Database Advanced Application Developer's Guide for more information about OCCI

- Oracle C++ Call Interface Programmer's Guide for complete information about OCCI

Open Database Connectivity (ODBC)

Open Database Connectivity (ODBC) is a set of database access APIs that connect to the database, prepare, and then run SQL statements on the database. An application that uses an ODBC driver can access non-uniform data sources, such as spreadsheets and comma-delimited files.

The Oracle ODBC driver conforms to ODBC 3.51 specifications. It supports all core APIs and a subset of Level 1 and Level 2 functions. Microsoft supplies the Driver manager component for the Windows platform.

Like OCI, OCCI, and JDBC, ODBC is part of the Oracle Instant Client installation.

See Also:

- Oracle Database Concepts

- Oracle Services for Microsoft Transaction Server Developer's Guide for information about using the Oracle ODBC driver with Windows

- Oracle Database Administrator's Reference for Linux and UNIX-Based Operating Systems for information about using Oracle ODBC driver on Linux

Pro*C/C++ Precompiler

The Pro*C/C++ precompiler enables you to embed SQL statements in a C or C++ source file. The precompiler accepts the source program as input, translates the embedded SQL statements into standard Oracle run-time library calls, and generates a modified source program that you can compile, link, and run.

See Also:

- Oracle Database Concepts for more information about Oracle precompilers

- Oracle Database Advanced Application Developer's Guide for more information about the Pro*C/C++ precompiler

- Pro*C/C++ Programmer's Guide for complete information about the Pro*C/C++ precompiler

Pro*COBOL Precompiler

The Pro*COBOL precompiler enables you to embed SQL statements in a COBOL source file. The precompiler accepts the source program as input, translates the embedded SQL statements into standard Oracle run-time library calls, and generates a modified source program that you can compile, link, and run.

See Also:

- Oracle Database Concepts for more information about Oracle precompilers

- Oracle Database Advanced Application Developer's Guide for more information about the Pro*COBOL precompiler

- Pro*COBOL Programmer's Guide for complete information about the Pro*COBOL precompiler

Microsoft .NET Framework

The Microsoft .NET Framework is a multilanguage environment for building, deploying, and running applications and XML Web services. Its main components are:

- Common Language Runtime (CLR)
The Common Language Runtime (CLR) is a language-neutral development and run-time environment that provides services that help manage running applications.

- Framework Class Libraries (FCL)
The Framework Class Libraries (FCL) provide a consistent, object-oriented library of prepackaged functionality.

Oracle Data Provider for .NET (ODP.NET)

Oracle Data Provider for .NET (ODP.NET) provides fast and efficient ADO.NET data access from .NET client applications to Oracle Database and access to other Oracle Database features.

ODP.NET allows developers to take advantage of advanced Oracle Database functionality, including Real Application Clusters, XML DB, and advanced security.

Oracle Developer Tools for Visual Studio (ODT)

Oracle Developer Tools for Visual Studio (ODT) is a set of application tools that integrate with the Visual Studio environment. These tools provide graphic user interface access to Oracle functionality, enable the user to perform a wide range of application development tasks, and improve development productivity and ease of use. Oracle Developer Tools supports the programming and implementation of .NET stored procedures using Visual Basic, C#, and other .NET languages.

.NET Stored Procedures

Oracle Database Extensions for .NET is a database option for Oracle Database on Windows. It makes it possible to build and run .NET stored procedures or functions with Oracle Database for Microsoft Windows using Visual Basic .NET or Visual C#.

After building .NET procedures and functions into a .NET assembly, you can deploy them in Oracle Database using the Oracle Deployment Wizard for .NET, a component of the Oracle Developer Tools for Visual Studio.

Oracle Providers for ASP.NET

Oracle Providers for ASP.NET offer ASP.NET developers an easy way to store state common to Web applications within Oracle Database. These providers are modeled on existing Microsoft ASP.NET providers, sharing similar schema and programming interfaces to provide .NET developers a familiar interface. Oracle supports the Membership, Profile, Role, and other providers.

See Also:

- Oracle Database 2 Day + .NET Developer's Guide

- Oracle Data Provider for .NET Developer's Guide for Microsoft Windows

- Oracle Database Extensions for .NET Developer's Guide for Microsoft Windows

- Oracle Database Advanced Application Developer's Guide

Oracle Provider for OLE DB (OraOLEDB)

Oracle Provider for OLE DB (OraOLEDB) is an open standard data access methodology that uses a set of Component Object Model (COM) interfaces for accessing and manipulating different types of data. These interfaces are available from various database providers.

See Also:

Oracle Provider for OLE DB Developer's Guide for more information about OraOLEDB

Oracle Objects for OLE (OO4O)

Oracle Objects for OLE (OO4O) provides easy access to data stored in Oracle Database with any programming or scripting language that supports the Microsoft COM Automation and ActiveX technology, including Visual Basic, Visual C++, Visual Basic For Applications (VBA), IIS Active Server Pages (VBScript and JavaScript).

See Also:

- Oracle Database Advanced Application Developer's Guide for more information about OO4O

- Oracle Objects for OLE Help, and Oracle Objects for OLE C++ Class Library Help, for detailed information about Oracle Objects for OLE

- Oracle Database SecureFiles and Large Objects Developer's Guide for examples of how to use Oracle Objects for OLE

- Oracle Streams Advanced Queuing User's Guide for examples of how to use Oracle Objects for OLE

About Sample Schema HR

The HR schema is a sample schema that can be installed as part of Oracle Database. This schema contains information about employees—their departments, locations, work histories, and related information. Like all schemas, the HR schema has tables, views, indexes, procedures, functions, and other attributes of a database schema.

The examples and tutorials in this document use the HR schema.

See Also:

- Oracle Database Sample Schemas for a complete description of the HR schema

- "Connecting to Oracle Database as User HR" for instructions for connecting to Oracle Database as the user HR

2 Connecting to Oracle Database

You can connect to Oracle Database only through a client program, such as SQL*Plus or SQL Developer.

This chapter contains the following sections:

- Connecting to Oracle Database from SQL*Plus

- Connecting to Oracle Database from SQL Developer

- Connecting to Oracle Database as User HR

Connecting to Oracle Database from SQL*Plus

SQL*Plus is a client program with which you can access Oracle Database. This section shows how to start SQL*Plus and connect to Oracle Database.

Note:

For steps 3 and 4 of the following procedure, you need a user name and password.

To connect to Oracle Database from SQL*Plus:

1. If you are on a Windows system, display a Windows command prompt.

2. At the command prompt, type sqlplus and press the key Enter.

SQL*Plus starts and prompts you for your user name.

3. Type your user name and press the key Enter.

SQL*Plus prompts you for your password.

4. Type your password and press the key Enter.

Note:

For security, your password is not visible on your screen.

The system connects you to an Oracle Database instance.

You are in the SQL*Plus environment. At the SQL> prompt, you can enter and run SQL*Plus commands, SQL statements, PL/SQL statements, and operating system commands.

To exit SQL*Plus, type exit and press the key Enter.

Note:

Exiting SQL*Plus ends the SQL*Plus session, but does not shut down the Oracle Database instance.

Example 2-1 starts SQL*Plus, connects to Oracle Database, runs a SQL SELECT statement, and exits SQL*Plus. User input is bold.

Example 2-1 Connecting to Oracle Database from SQL*Plus

> sqlplus
SQL*Plus: Release 11.2.0.0.1 - Beta on Mon Jun 9 15:31:26 2008

Copyright (c) 1982, 2008, Oracle.  All rights reserved.

Enter user-name: your_user_name
Enter password: your_password

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.0.0 - Development
With the Partitioning, Data Mining and Real Application Testing options

SQL> select count(*) from employees;

COUNT(*)
----------
107

SQL> exit

Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.0.0 - Development
With the Partitioning, Data Mining and Real Application Testing options
>

See Also:

- "Connecting to Oracle Database as User HR from SQL*Plus"

- "About SQL*Plus" for a brief description of SQL*Plus

- SQL*Plus User's Guide and Reference for more information about starting SQL*Plus and connecting to Oracle Database

Connecting to Oracle Database from SQL Developer

SQL Developer is a client program with which you can access Oracle Database. This section assumes that SQL Developer is installed on your system, and shows how to start it and connect to Oracle Database. If SQL Developer is not installed on your system, see Oracle Database SQL Developer User's Guide for installation instructions.

Note:

For the following procedure:

- The first time you start SQL Developer on your system, you must provide the full path to java.exe in step 4.

- For step 7, you need a user name and password.

- For step 9, you need a host name and port.

To connect to Oracle Database from SQL Developer:

1. Access the menu from which you can select SQL Developer:

- On a Windows system: From the Start menu, select All Programs.

- On a Linux system:

- On Gnome: Click Application.

- On KDE: Click K.

2. Select Oracle - ORACLE_HOME.

3. Select Application Development.

4. Select SQL Developer.

If this is the first time you have started SQL Developer on your system, you are prompted to enter the full path to java.exe (for example, C:\jdk1.5.0\bin\java.exe). Either type the full path after the prompt or browse to it, and then press the key Enter.

The Oracle SQL Developer window opens.

5. In the navigation frame of the window, click Connections.
The Connections pane appears.

6. In the Connections pane, click the icon New Connection.
The New/Select Database Connection window opens.

7. In the New/Select Database Connection window, type the appropriate values in the fields Connection Name, Username, and Password.

For security, the password characters that you type appear as asterisks.

Near the Password field is the check box Save Password. By default, it is deselected. Oracle recommends accepting the default.

8. In the New/Select Database Connection window, click the tab Oracle.
The Oracle pane appears.

9. In the Oracle pane:

- For Role, accept the default.

- For Connection Type, accept the default (Basic).

- In the fields Hostname and Port, type the appropriate values.

- Select the option SID.

- In the SID field, type the appropriate value.

10. In the New/Select Database Connection window, click the button Test.
The connection is tested. If the connection succeeds, the Status indicator changes from blank to Success.

11. If the test succeeded, click the button Connect.

The New/Select Database Connection window closes. The Connections pane shows the connection whose name you entered in the Connection Name field in step 7.

You are in the SQL Developer environment.

To exit SQL Developer, select Exit from the File menu.

Note:

Exiting SQL Developer ends the SQL Developer session, but does not shut down the Oracle Database instance. The next time you start SQL Developer, the connection you created using the preceding procedure still exists. SQL Developer prompts you for the password that you supplied in step 7 (unless you selected the check box Save Password).

See Also:

- "Connecting to Oracle Database as User HR from SQL Developer"

- "About SQL Developer" for a brief description of SQL Developer

- Oracle Database SQL Developer User's Guide for more information about using SQL Developer to create connections to Oracle Database

Connecting to Oracle Database as User HR

This section shows how to unlock the HR account and connect to Oracle Database as the user HR, who owns the HR sample schema that the examples and tutorials in this document use.

To do the tutorials and examples in this document, and create the sample application, you must connect to Oracle Database as the user HR from SQL Developer. The HR sample schema is the development environment for the sample application.

Topics:

- Unlocking the HR Account

- Connecting to Oracle Database as User HR from SQL*Plus

- Connecting to Oracle Database as User HR from SQL Developer

Unlocking the HR Account

By default, when the HR schema is installed, the HR account is locked and its password is expired. You can connect to Oracle Database as the user HR only if the HR account is unlocked.

Note:

For the following procedure, you need the name and password of a user who has the ALTER USER system privilege (for example, SYSTEM).

To unlock the HR account and reset its password:

1. Using SQL*Plus, connect to Oracle Database as a user with the ALTER USER system privilege.
For instructions, see "Connecting to Oracle Database from SQL*Plus".

2. At the SQL> prompt, unlock the HR account and reset its password:

Caution:

Choose a secure password. For guidelines for securing passwords, see Oracle Database Security Guide.

ALTER USER HR ACCOUNT UNLOCK IDENTIFIED BY password;

The system responds:

User altered

The HR account is unlocked and its password is password.

Now you can connect to Oracle Database as user HR with the password password. For instructions, see either "Connecting to Oracle Database from SQL*Plus" or "Connecting to Oracle Database from SQL Developer".

See Also:

- Oracle Database 2 Day + Security Guide for information about predefined user accounts provided by Oracle Database, including HR

- Oracle Database SQL Developer User's Guide for information about accessing SQL*Plus within SQL Developer

- Oracle Database 2 Day DBA for information about using Enterprise Manager to unlock user accounts

Connecting to Oracle Database as User HR from SQL*Plus

This section shows how to connect to Oracle Database as the user HR from SQL*Plus, if the HR account is unlocked.

To connect to Oracle Database as user HR from SQL*Plus:

Note:

For this task, you need the password for the HR account.

1. If you are connected to Oracle Database, close your current connection.

2. Follow the directions in "Connecting to Oracle Database from SQL*Plus", entering the user name HR at step 3 and the password for the HR account at step 4.
You are now connected to Oracle Database as the user HR.

See Also:

SQL*Plus User's Guide and Reference for an example of using SQL*Plus to create an HR connection

Connecting to Oracle Database as User HR from SQL Developer

This section shows how to connect to Oracle Database as the user HR from SQL Developer, if the HR account is unlocked.

Note:

For the following procedure, you need the password for the HR account.

To connect to Oracle Database as user HR from SQL Developer:

- Follow the directions in "Connecting to Oracle Database from SQL Developer", entering the following values at steps 7 and 9.
At step 7:

- For Connection Name, enter hr_conn.
(You can enter a different name, but the tutorials in this document assume that you named the connection hr_conn.)

- For Username, enter HR.

- For Password, enter the password for the HR account.

At step 9:

- For Role, accept the default.

- For Connection Type, accept the default (Basic).

- For Hostname, enter localhost.

- For Port, enter 1521.

- For SID, enter orcl.

At step 11, the name of the connection, hr_conn, appears in the Connections pane of the Oracle SQL Developer window.

You are now connected to Oracle Database as the user HR.

3 Exploring Oracle Database with SQL Developer

This chapter contains the following topics:

- Tutorial: Viewing HR Schema Objects

- Tutorial: Viewing EMPLOYEES Table Properties and Data

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

Tutorial: Viewing HR Schema Objects

This tutorial shows how to use SQL Developer to view the objects that belong to the HR schema. This is called browsing the HR schema.

To browse the HR schema:

1. In the navigation frame, click the tab Connections.
The Connections pane shows the hr_conn icon. To the left of the icon is a plus sign (+).

2. Click the plus sign.
If you are not connected to the database, the Connection Information window opens. If you are connected to the database, the hr_conn information expands (see the information that follows "Click OK" in step 3).

3. If the Connection Information window opens:

1. In the User Name field, enter hr.

2. In the Password field, enter the password for the user hr.

3. Click OK.

The hr_conn information expands: The plus sign becomes a minus sign, and under the hr_conn icon, a list of schema object types appears—Tables, Views, Indexes, and so on. (If you click the minus sign, the hr_conn information collapses: The minus sign becomes a plus sign, and the list disappears.)

See Also:

- "About Schema Objects" for brief descriptions of the schema object types

- Oracle Database SQL Developer User's Guide for more information about the SQL Developer user interface

Tutorial: Viewing EMPLOYEES Table Properties and Data

This tutorial shows how to use SQL Developer to view the properties and data of the EMPLOYEES table in the HR schema, if you are browsing the HR schema.

If you are not browsing the HR schema, follow the instructions in "Tutorial: Viewing HR Schema Objects" and then return to this topic.

To view the properties and data of the EMPLOYEES table:

1. In the Connections pane, expand Tables.
Under Tables, a list of the tables in the HR schema appears.

2. Select the table EMPLOYEES.
In the right frame of the Oracle SQL Developer window, in the Columns pane, a list of all columns of this table appears. To the right of each column are its properties—name, data type, and so on. (To see all column properties, move the horizontal scroll bar to the right.)

3. In the right frame, click the tab Data.

The Data pane appears, showing a numbered list of all records in this table. (To see more records, move the vertical scroll bar down. To see more columns of the records, move the horizontal scroll bar to the right.)

4. In the right frame, click the tab Constraints.
The Constraints pane appears, showing a list of all constraints on this table. To the right of each constraint are its properties—name, type, search condition, and so on. (To see all constraint properties, move the horizontal scroll bar to the right.)

5. Explore the other properties by clicking on the appropriate tabs.

See Also:

- Oracle Database SQL Developer User's Guide for more information about the SQL Developer user interface

- Chapter 4, "Selecting Table Data," for information about using queries to see table data

4 Selecting Table Data

This chapter contains the following topics:

- About Queries

- Running Queries in SQL Developer

- Tutorial: Selecting All Columns of a Table

- Tutorial: Selecting Specific Columns of a Table

- Displaying Selected Columns Under New Headings

- Selecting Data that Satisfies Specified Conditions

- Specifying Conditions with Regular Expressions

- Sorting Selected Data

- Selecting Data from Multiple Tables

- Using Operators and Functions in Queries

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

About Queries

A query, or SQL SELECT statement, selects data from one or more tables or views.

The simplest form of query has this syntax:

SELECT select_list FROM source_list

The select_list specifies the columns from which the data is to be selected, and the source_list specifies the tables or views that have these columns.

A query nested within another SQL statement is called a subquery.

In the SQL*Plus environment, you can enter a query after the SQL> prompt.

In the SQL Developer environment, you can enter a query in the SQL Worksheet. For instructions, see "Running Queries in SQL Developer".

Note:

When the result of a query is displayed, records can be in any order, unless you specify their order with the ORDER BY clause. For more information, see "Sorting Selected Data".

See Also:

- Oracle Database SQL Language Reference for more information about queries and subqueries

- Oracle Database SQL Language Reference for more information about the SELECT statement

- SQL*Plus User's Guide and Reference for more information about the SQL*Plus command line interface

- Oracle Database SQL Developer User's Guide for information about using the SQL Worksheet in SQL Developer

Running Queries in SQL Developer

This topic explains how to run queries or other SQL statements in SQL Developer, if you are connected to Oracle Database as user HR from SQL Developer (for instructions, see "Connecting to Oracle Database as User HR from SQL Developer").

To run queries in SQL Developer:

1. Click the icon SQL Worksheet.
Either the Connection Information window opens or the SQL Worksheet pane appears.

2. If the Select Connection window opens:

1. If the Connection field does not have the value hr_conn, select that value from the drop-down list.

2. Click OK.

The SQL Worksheet pane appears. Under "Enter SQL Statement:" is a field where you can enter a SQL statement.

3. In the SQL Worksheet pane, type a query (a SELECT statement).

4. Click the icon Execute Statement.
The query runs.

5. Click the tab Results.
The Results pane appears, showing the result of the query.

6. Click the icon Clear.
The query and its results disappear, and you can enter another SQL statement in the SQL Worksheet.

See Also:

Oracle Database SQL Developer User's Guide for information about using the SQL Worksheet in SQL Developer

Tutorial: Selecting All Columns of a Table

This tutorial shows how to select all columns of the EMPLOYEES table.

To select all columns of the EMPLOYEES Table:

1. Click the icon SQL Worksheet.
The SQL Worksheet pane appears.

2. In the field under "Enter SQL Statement:", enter this query:

SELECT * FROM EMPLOYEES;

3. Click the Execute Statement.
The query runs.

4. Click the tab Results.
The Results pane appears, showing the result of the query.

See Also:

"Tutorial: Viewing EMPLOYEES Table Properties and Data" for information about another way to view table data with SQL Developer

Tutorial: Selecting Specific Columns of a Table

This tutorial shows how to select only the columns FIRST_NAME, LAST_NAME, and DEPARTMENT_ID of the EMPLOYEES table.

To select only FIRST_NAME, LAST_NAME, and DEPARTMENT_ID:

1. Click the icon SQL Worksheet.
The SQL Worksheet pane appears.

2. In the field under "Enter SQL Statement:", enter this query:

SELECT FIRST_NAME, LAST_NAME, DEPARTMENT_ID
FROM EMPLOYEES;

3. Click the icon Execute Statement.
The query runs.

4. Click the tab Results.
The Results pane appears, showing the results of the query, which are similar to:

FIRST_NAME           LAST_NAME                 DEPARTMENT_ID
-------------------- ------------------------- -------------
Donald               OConnell                             50
Douglas              Grant                                50
Jennifer             Whalen                               10
Michael              Hartstein                            20
Pat                  Fay                                  20
Susan                Mavris                               40
Hermann              Baer                                 70
Shelley              Higgins                             110
William              Gietz                               110
Steven               King                                 90
Neena                Kochhar                              90

FIRST_NAME           LAST_NAME                 DEPARTMENT_ID
-------------------- ------------------------- -------------
Lex                  De Haan                              90
...
Kevin                Feeney                               50

107 rows selected.

Displaying Selected Columns Under New Headings

When query results are displayed, the default column heading is the column name. To display a column under a new heading, specify the new heading (alias) immediately after the name of the column. The alias renames the column for the duration of the query, but does not change its name in the database.

The query in Example 4-1 selects the same columns as the query in Tutorial: Selecting Specific Columns of a Table, but it also specifies aliases for them. Because the aliases are not enclosed in double quotation marks, they are displayed in uppercase letters.

Example 4-1 Displaying Selected Columns Under New Headings

SELECT FIRST_NAME First, LAST_NAME last, DEPARTMENT_ID DepT
FROM EMPLOYEES;

Result is similar to:

FIRST                LAST                            DEPT
-------------------- ------------------------- ----------
Donald               OConnell                          50
Douglas              Grant                             50
Jennifer             Whalen                            10
Michael              Hartstein                         20
Pat                  Fay                               20
Susan                Mavris                            40
Hermann              Baer                              70
Shelley              Higgins                          110
William              Gietz                            110
Steven               King                              90
Neena                Kochhar                           90

FIRST                LAST                            DEPT
-------------------- ------------------------- ----------
Lex                  De Haan                           90
...
Kevin                Feeney                            50

107 rows selected.

If you enclose column aliases in double quotation marks, case is preserved, and the aliases can include spaces, as in Example 4-2.

Example 4-2 Preserving Case and Including Spaces in Column Aliases

SELECT FIRST_NAME "Given Name", LAST_NAME "Family Name"
FROM EMPLOYEES;

Result is similar to:

Given Name           Family Name
-------------------- -------------------------
Donald               OConnell
Douglas              Grant
Jennifer             Whalen
Michael              Hartstein
Pat                  Fay
Susan                Mavris
Hermann              Baer
Shelley              Higgins
William              Gietz
Steven               King
Neena                Kochhar

Given Name           Family Name
-------------------- -------------------------
Lex                  De Haan
...
Kevin                Feeney

107 rows selected.

See Also:

Oracle Database SQL Language Reference for more information about the SELECT statement, including the column alias (c_alias)

Selecting Data that Satisfies Specified Conditions

To select only data that matches a specified condition, include the WHERE clause in the SELECT statement. The condition in the WHERE clause can be any SQL condition (for information about SQL conditions, see Oracle Database SQL Language Reference).

The query in Example 4-3 selects data only for employees in department 90.

Example 4-3 Selecting Data from One Department

SELECT FIRST_NAME, LAST_NAME, DEPARTMENT_ID
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 90;

Result is similar to:

FIRST_NAME           LAST_NAME                 DEPARTMENT_ID
-------------------- ------------------------- -------------
Steven               King                                 90
Neena                Kochhar                              90
Lex                  De Haan                              90

The query in Example 4-4 selects data only for employees in departments 100, 110, and 120.

Example 4-4 Selecting Data from Specified Departments

SELECT FIRST_NAME, LAST_NAME, DEPARTMENT_ID
FROM EMPLOYEES
WHERE DEPARTMENT_ID IN (100, 110, 120);

Result is similar to:

FIRST_NAME           LAST_NAME                 DEPARTMENT_ID
-------------------- ------------------------- -------------
John                 Chen                                100
Daniel               Faviet                              100
William              Gietz                               110
Nancy                Greenberg                           100
Shelley              Higgins                             110
Luis                 Popp                                100
Ismael               Sciarra                             100
Jose Manuel          Urman                               100

8 rows selected.

There are no employees in department 120.

The query in Example 4-5 selects data only for employees whose last names start with "Ma".

Example 4-5 Selecting Data for Last Names that Start with the Same Substring

SELECT FIRST_NAME, LAST_NAME
FROM EMPLOYEES
WHERE LAST_NAME LIKE 'Ma%';

Result is similar to:

FIRST_NAME           LAST_NAME
-------------------- -------------------------
Jason                Mallin
Steven               Markle
James                Marlow
Mattea               Marvins
Randall              Matos
Susan                Mavris

6 rows selected.

The query in Example 4-6 selects data only for employees whose last names include "ma".

Example 4-6 Selecting Data for Last Names that Include the Same Substring

SELECT FIRST_NAME, LAST_NAME
FROM EMPLOYEES
WHERE LAST_NAME LIKE '%ma%';

Result is similar to:

FIRST_NAME           LAST_NAME
-------------------- -------------------------
Sundita              Kumar
Jose Manuel          Urman
Shanta               Vollman

The query in Example 4-7 tests for two conditions—whether the salary is at least 11000, and whether the commission percentage is not null.

Example 4-7 Selecting Data that Satisfies Two Conditions

SELECT FIRST_NAME, LAST_NAME, SALARY, COMMISSION_PCT "%"
FROM EMPLOYEES
WHERE (SALARY >= 11000) AND (COMMISSION_PCT IS NOT NULL);

Result is similar to:

FIRST_NAME           LAST_NAME                     SALARY          %
-------------------- ------------------------- ---------- ----------
John                 Russell                        14000         .4
Karen                Partners                       13500         .3
Alberto              Errazuriz                      12000         .3
Gerald               Cambrault                      11000         .3
Lisa                 Ozer                           11500        .25
Ellen                Abel                           11000         .3

6 rows selected.

See Also:

- Oracle Database SQL Language Reference for more information about the SELECT statement, including the WHERE clause

- Oracle Database SQL Language Reference for more information about SQL conditions

Specifying Conditions with Regular Expressions

As stated in "Selecting Data that Satisfies Specified Conditions", the condition in the WHERE clause can be any SQL condition. This topic shows how to specify conditions with SQL functions that accept regular expressions. A regular expression defines a search pattern, using metacharacters to specify search algorithms and literals to specify characters.

Suppose that you want to select all managers in the EMPLOYEES table. The JOB_ID of a manager ends with either '_MGR' or '_MAN', depending on the department. Therefore, the search pattern must be a regular expression, and you must use the REGEXP_LIKE function, as in Example 4-8.

In the regular expression (_m[an|gr]), the metacharacter | indicates the OR condition. The third function parameter, 'i', specifies that the match is case-insensitive.

Example 4-8 Selecting All Managers in the EMPLOYEES Table

SELECT FIRST_NAME, LAST_NAME, JOB_ID
FROM EMPLOYEES
WHERE REGEXP_LIKE(JOB_ID, '(_m[an|gr])', 'i');

Result is similar to:

FIRST_NAME           LAST_NAME                 JOB_ID
-------------------- ------------------------- ----------
Michael              Hartstein                 MK_MAN
Shelley              Higgins                   AC_MGR
Nancy                Greenberg                 FI_MGR
Den                  Raphaely                  PU_MAN
Matthew              Weiss                     ST_MAN
Adam                 Fripp                     ST_MAN
Payam                Kaufling                  ST_MAN
Shanta               Vollman                   ST_MAN
Kevin                Mourgos                   ST_MAN
John                 Russell                   SA_MAN
Karen                Partners                  SA_MAN

FIRST_NAME           LAST_NAME                 JOB_ID
-------------------- ------------------------- ----------
Alberto              Errazuriz                 SA_MAN
Gerald               Cambrault                 SA_MAN
Eleni                Zlotkey                   SA_MAN

14 rows selected.

Suppose that you want to select every employee whose last name has a double vowel (two adjacent occurrences of the same vowel). Example 4-9 shows how you can do this.

The regular expression ([AEIOU]) represents any vowel. The metacharacter \1 represents the first (and in this case, only) regular expression. The third function parameter, 'i', specifies that the match is case-insensitive.

Example 4-9 Selecting All Employees Whose Last Names Have Double Vowels

SELECT FIRST_NAME, LAST_NAME
FROM EMPLOYEES
WHERE REGEXP_LIKE(LAST_NAME, '([AEIOU])\1', 'i');

Result is similar to:

FIRST_NAME           LAST_NAME
-------------------- -------------------------
Harrison             Bloom
Lex                  De Haan
Kevin                Feeney
Ki                   Gee
Nancy                Greenberg
Danielle             Greene
Alexander            Khoo
David                Lee

8 rows selected.

Suppose that, in the displayed query results, you want to replace phone numbers that are stored in the format nnn.nnn.nnnn with their equivalents in the format (nnn) nnn-nnnn. You can use the REGEXP_REPLACE function, with regular expressions in the search pattern (the stored format) and references to those regular expressions in the replace string (the display format), as in Example 4-10.

The search pattern has three regular expressions, each of which is enclosed in parentheses. The metacharacter [[:digit:]] represents a digit, the metacharacter {n} specifies n occurrences, and the metacharacter \ is an escape character. The character immediately after an escape character is interpreted as a literal. Without the escape character, the metacharacter . represents any character.

The replace string uses \1, \2, and \3 to represent the first, second, and third regular expressions in the search pattern, respectively. (In the replace string, \ is not an escape character.)

Example 4-10 Displaying Phone Numbers in a Different Format

SELECT PHONE_NUMBER "Old Format",
REGEXP_REPLACE(PHONE_NUMBER,
'([[:digit:]]{3})\.([[:digit:]]{3})\.([[:digit:]]{4})',
'(\1) \2-\3') "New Format"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 90;

Result is similar to:

Old Format          New Format
-------------------- ---------------------------------------------------------
515.123.4567         (515) 123-4567
515.123.4568         (515) 123-4568
515.123.4569         (515) 123-4569

Suppose that you want to extract the street number from each STREET_ADDRESS in the LOCATIONS table. Some street numbers include hyphens, so the search pattern must use a regular expression, and you must use the REGEXP_SUBSTR function, as in Example 4-11.

Example 4-11 Extracting the Street Number from Each STREET_ADDRESS

COLUMN Number FORMAT A8
SELECT STREET_ADDRESS "Address",
REGEXP_SUBSTR(STREET_ADDRESS, '[[:digit:]-]+') "Number"
FROM LOCATIONS;
COLUMN Number CLEAR

Result is similar to:

Address                                  Number
---------------------------------------- --------
1297 Via Cola di Rie                     1297
93091 Calle della Testa                  93091
2017 Shinjuku-ku                         2017
9450 Kamiya-cho                          9450
2014 Jabberwocky Rd                      2014
2011 Interiors Blvd                      2011
2007 Zagora St                           2007
2004 Charade Rd                          2004
147 Spadina Ave                          147
6092 Boxwood St                          6092
40-5-12 Laogianggen                      40-5-12

Address                                  Number
---------------------------------------- --------
1298 Vileparle (E)                       1298
12-98 Victoria Street                    12-98
198 Clementi North                       198
8204 Arthur St                           8204
Magdalen Centre, The Oxford Science Park
9702 Chester Road                        9702
Schwanthalerstr. 7031                    7031
Rua Frei Caneca 1360                     1360
20 Rue des Corps-Saints                  20
Murtenstrasse 921                        921
Pieter Breughelstraat 837                837

Address                                  Number
---------------------------------------- --------
Mariano Escobedo 9991                    9991

23 rows selected.

To count the number of spaces in each STREET_ADDRESS, you can use the REGEXP_COUNT function, as in Example 4-12.

Example 4-12 Counting the Number of Spaces in Each STREET_ADDRESS

SELECT STREET_ADDRESS,
REGEXP_COUNT(STREET_ADDRESS, ' ') "Number of Spaces"
FROM LOCATIONS;

Result is similar to:

STREET_ADDRESS                           Number of Spaces
---------------------------------------- ----------------
1297 Via Cola di Rie                                    4
93091 Calle della Testa                                 3
2017 Shinjuku-ku                                        1
9450 Kamiya-cho                                         1
2014 Jabberwocky Rd                                     2
2011 Interiors Blvd                                     2
2007 Zagora St                                          2
2004 Charade Rd                                         2
147 Spadina Ave                                         2
6092 Boxwood St                                         2
40-5-12 Laogianggen                                     1

STREET_ADDRESS                           Number of Spaces
---------------------------------------- ----------------
1298 Vileparle (E)                                      2
12-98 Victoria Street                                   2
198 Clementi North                                      2
8204 Arthur St                                          2
Magdalen Centre, The Oxford Science Park                5
9702 Chester Road                                       2
Schwanthalerstr. 7031                                   1
Rua Frei Caneca 1360                                    4
20 Rue des Corps-Saints                                 3
Murtenstrasse 921                                       1
Pieter Breughelstraat 837                               2

STREET_ADDRESS                           Number of Spaces
---------------------------------------- ----------------
Mariano Escobedo 9991                                   2

23 rows selected.

To report the position of the first space in each STREET_ADDRESS, you can use the REGEXP_INSTR function, as in Example 4-13.

Example 4-13 Reporting the Position of the First Space in Each STREET_ADDRESS

SELECT STREET_ADDRESS,
REGEXP_INSTR(STREET_ADDRESS, ' ') "First Space"
FROM LOCATIONS;

Result is similar to:

STREET_ADDRESS                           First Space
---------------------------------------- -----------
1297 Via Cola di Rie                               5
93091 Calle della Testa                            6
2017 Shinjuku-ku                                   5
9450 Kamiya-cho                                    5
2014 Jabberwocky Rd                                5
2011 Interiors Blvd                                5
2007 Zagora St                                     5
2004 Charade Rd                                    5
147 Spadina Ave                                    4
6092 Boxwood St                                    5
40-5-12 Laogianggen                                8

STREET_ADDRESS                           First Space
---------------------------------------- -----------
1298 Vileparle (E)                                 5
12-98 Victoria Street                              6
198 Clementi North                                 4
8204 Arthur St                                     5
Magdalen Centre, The Oxford Science Park           9
9702 Chester Road                                  5
Schwanthalerstr. 7031                             17
Rua Frei Caneca 1360                               4
20 Rue des Corps-Saints                            3
Murtenstrasse 921                                 14
Pieter Breughelstraat 837                          7

STREET_ADDRESS                           First Space
---------------------------------------- -----------
Mariano Escobedo 9991                              8

23 rows selected.

See Also:

- Oracle Database Advanced Application Developer's Guide for more information about using regular expressions in database applications

- Oracle Database SQL Language Reference for syntax of regular expressions

- Oracle Database SQL Language Reference for more information about the REGEXP_LIKE expression

- Oracle Database SQL Language Reference for more information about the REGEXP_REPLACE expression

- Oracle Database SQL Language Reference for more information about the REGEXP_SUBSTR expression

- Oracle Database SQL Language Reference for more information about the REGEXP_COUNT expression

- Oracle Database SQL Language Reference for more information about the REGEXP_INSTR expression

Sorting Selected Data

When the results of a query are displayed, records can be in any order, unless you specify their order with the ORDER BY clause.

The results of the query in Example 4-14 are sorted by LAST_NAME, in ascending order (the default).

Alternatively, in SQL Developer, you can omit the ORDER BY clause and double-click the name of the column to sort.

Example 4-14 Sorting Selected Data by LAST_NAME

SELECT FIRST_NAME, LAST_NAME, HIRE_DATE
FROM EMPLOYEES
ORDER BY LAST_NAME;

Result:

FIRST_NAME           LAST_NAME                 HIRE_DATE
-------------------- ------------------------- ---------
Ellen                Abel                      11-MAY-96
Sundar               Ande                      24-MAR-00
Mozhe                Atkinson                  30-OCT-97
David                Austin                    25-JUN-97
Hermann              Baer                      07-JUN-94
Shelli               Baida                     24-DEC-97
Amit                 Banda                     21-APR-00
Elizabeth            Bates                     24-MAR-99
...
FIRST_NAME           LAST_NAME                 HIRE_DATE
-------------------- ------------------------- ---------
Jose Manuel          Urman                     07-MAR-98
Peter                Vargas                    09-JUL-98
Clara                Vishney                   11-NOV-97
Shanta               Vollman                   10-OCT-97
Alana                Walsh                     24-APR-98
Matthew              Weiss                     18-JUL-96
Jennifer             Whalen                    17-SEP-87
Eleni                Zlotkey                   29-JAN-00

107 rows selected

The sort criterion need not be included in the select list, as Example 4-15 shows.

Example 4-15 Sorting Selected Data by an Unselected Column

SELECT FIRST_NAME, HIRE_DATE
FROM EMPLOYEES
ORDER BY LAST_NAME;

Result:

FIRST_NAME           HIRE_DATE
-------------------- ---------
Ellen                11-MAY-96
Sundar               24-MAR-00
Mozhe                30-OCT-97
David                25-JUN-97
Hermann              07-JUN-94
Shelli               24-DEC-97
Amit                 21-APR-00
Elizabeth            24-MAR-99
...
FIRST_NAME           HIRE_DATE
-------------------- ---------
Jose Manuel          07-MAR-98
Peter                09-JUL-98
Clara                11-NOV-97
Shanta               10-OCT-97
Alana                24-APR-98
Matthew              18-JUL-96
Jennifer             17-SEP-87
Eleni                29-JAN-00

107 rows selected.

See Also:

Oracle Database SQL Language Reference for more information about the SELECT statement, including the ORDER BY clause

Selecting Data from Multiple Tables

Suppose that you want to select the FIRST_NAME, LAST_NAME, and DEPARTMENT_NAME of every employee. FIRST_NAME and LAST_NAME are in the EMPLOYEES table, and DEPARTMENT_NAME is in the DEPARTMENTS table. Both tables have DEPARTMENT_ID. You can use the query in Example 4-16. Such a query is called a join.

Example 4-16 Selecting Data from Two Tables (Joining Two Tables)

SELECT EMPLOYEES.FIRST_NAME "First",
EMPLOYEES.LAST_NAME "Last",
DEPARTMENTS.DEPARTMENT_NAME "Dept. Name"
FROM EMPLOYEES, DEPARTMENTS
WHERE EMPLOYEES.DEPARTMENT_ID = DEPARTMENTS.DEPARTMENT_ID;

Result:

First                Last                      Dept. Name
-------------------- ------------------------- ------------------------------
Jennifer             Whalen                    Administration
Michael              Hartstein                 Marketing
Pat                  Fay                       Marketing
Den                  Raphaely                  Purchasing
Karen                Colmenares                Purchasing
Alexander            Khoo                      Purchasing
Shelli               Baida                     Purchasing
Sigal                Tobias                    Purchasing
Guy                  Himuro                    Purchasing
Susan                Mavris                    Human Resources
Donald               OConnell                  Shipping

First                Last                      Dept. Name
-------------------- ------------------------- ------------------------------
Douglas              Grant                     Shipping
...
Shelley              Higgins                   Accounting

106 rows selected.

Table-name qualifiers are optional for column names that appear in only one table of a join, but are required for column names that appear in both tables. The following query is equivalent to the query in Example 4-16:

SELECT FIRST_NAME "First",
LAST_NAME "Last",
DEPARTMENT_NAME "Dept. Name"
FROM EMPLOYEES, DEPARTMENTS
WHERE EMPLOYEES.DEPARTMENT_ID = DEPARTMENTS.DEPARTMENT_ID;

To make queries that use qualified column names more readable, use table aliases, as in the following example:

SELECT FIRST_NAME "First",
LAST_NAME "Last",
DEPARTMENT_NAME "Dept. Name"
FROM EMPLOYEES e, DEPARTMENTS d
WHERE e.DEPARTMENT_ID = d.DEPARTMENT_ID;

Although you create the aliases in the FROM clause, you can use them earlier in the query, as in the following example:

SELECT e.FIRST_NAME "First",
e.LAST_NAME "Last",
d.DEPARTMENT_NAME "Dept. Name"
FROM EMPLOYEES e, DEPARTMENTS d
WHERE e.DEPARTMENT_ID = d.DEPARTMENT_ID;

See Also:

Oracle Database SQL Language Reference for more information about joins

Using Operators and Functions in Queries

The select_list of a query can include SQL expressions, which can include SQL operators and SQL functions. These operators and functions can have table data as operands and arguments. The SQL expressions are evaluated, and their values appear in the results of the query.

Topics:

- Using Arithmetic Operators in Queries

- Using Numeric Functions in Queries

- Using the Concatenation Operator in Queries

- Using Character Functions in Queries

- Using Datetime Functions in Queries

- Using Conversion Functions in Queries

- Using Aggregate Functions in Queries

- Using NULL-Related Functions in Queries

- Using CASE Expressions in Queries

- Using the DECODE Function in Queries

See Also:

- Oracle Database SQL Language Reference for more information about SQL operators

- Oracle Database SQL Language Reference for more information about SQL functions

Using Arithmetic Operators in Queries

SQL supports the basic arithmetic operators: + (addition), - (subtraction), * (multiplication), and / (division).

The query in Example 4-17 displays LAST_NAME, SALARY (monthly pay), and annual pay for each employee in department 90, in descending order of SALARY.

Example 4-17 Using an Arithmetic Expression in a Query

SELECT LAST_NAME,
SALARY "Monthly Pay",
SALARY * 12 "Annual Pay"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 90
ORDER BY SALARY DESC;

Result:

LAST_NAME                 Monthly Pay Annual Pay
------------------------- ----------- ----------
King                            24000     288000
De Haan                         17000     204000
Kochhar                         17000     204000

Using Numeric Functions in Queries

Numeric functions accept numeric input and return numeric values. Each numeric function returns a single value for each row that is evaluated. The numeric functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

The query in Example 4-18 uses the numeric function ROUND to display the daily pay of each employee in department 100, rounded to the nearest cent.

Example 4-18 Rounding Numeric Data

SELECT LAST_NAME,
ROUND (((SALARY * 12)/365), 2) "Daily Pay"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

LAST_NAME                  Daily Pay
------------------------- ----------
Chen                          269.59
Faviet                        295.89
Greenberg                     394.52
Popp                          226.85
Sciarra                       253.15
Urman                         256.44

6 rows selected.

The query in Example 4-19 uses the numeric function TRUNC to display the daily pay of each employee in department 100, truncated to the nearest dollar.

Example 4-19 Truncating Numeric Data

SELECT LAST_NAME,
TRUNC (((SALARY * 12)/365), 2) "Daily Pay"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

LAST_NAME                  Daily Pay
------------------------- ----------
Chen                             269
Faviet                           295
Greenberg                        394
Popp                             226
Sciarra                          253
Urman                            256

6 rows selected.

See Also:

Oracle Database SQL Language Reference for more information about SQL numeric functions

Using the Concatenation Operator in Queries

The concatenation operator (||) combines two strings into one string, by appending the second string to the first. For example, 'a'||'b'='ab'. You can use this operator to combine information from two columns or expressions in the same column of the report, as in the query in Example 4-20.

Example 4-20 Concatenating Character Data

SELECT FIRST_NAME || ' ' || LAST_NAME "Name"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

Name
----------------------------------------------
John Chen
Daniel Faviet
Nancy Greenberg
Luis Popp
Ismael Sciarra
Jose Manuel Urman

6 rows selected.

Using Character Functions in Queries

Character functions accept character input. Most return character values, but some return numeric values. Each character function returns a single value for each row that is evaluated. The character functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

The functions UPPER, INITCAP, and LOWER display their character arguments in uppercase, initial capital, and lowercase, respectively.

The query in Example 4-21 displays LAST_NAME in uppercase, FIRST_NAME with the first character in uppercase and all others in lowercase, and EMAIL in lowercase.

Example 4-21 Changing the Case of Character Data

SELECT UPPER(LAST_NAME) "Last",
INITCAP(FIRST_NAME) "First",
LOWER(EMAIL) "E-Mail"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY EMAIL;

Result:

Last                      First                E-Mail
------------------------- -------------------- -------------------------
FAVIET                    Daniel               dfaviet
SCIARRA                   Ismael               isciarra
CHEN                      John                 jchen
URMAN                     Jose Manuel          jmurman
POPP                      Luis                 lpopp
GREENBERG                 Nancy                ngreenbe

6 rows selected.

The functions LTRIM and RTRIM trim characters from the left and right ends of their character arguments, respectively. The function TRIM trims leading zeros, trailing zeros, or both.

The query in Example 4-22 finds every clerk in the EMPLOYEES table and trims '_CLERK' from the JOB_ID, displaying only the characters that identify the type of clerk.

Example 4-22 Trimming Character Data

SELECT LAST_NAME,
RTRIM(JOB_ID, '_CLERK') "Clerk Type"
FROM EMPLOYEES
WHERE JOB_ID LIKE '%_CLERK'
ORDER BY LAST_NAME;

Result:

LAST_NAME                 Clerk Type
------------------------- ----------
Atkinson                  ST
Baida                     PU
Bell                      SH
Bissot                    ST
Bull                      SH
Cabrio                    SH
Chung                     SH
Colmenares                PU
Davies                    ST
Dellinger                 SH
Dilly                     SH

LAST_NAME                 Clerk Type
------------------------- ----------
Everett                   SH
Feeney                    SH
...
LAST_NAME                 Clerk Type
------------------------- ----------
Walsh                     SH

45 rows selected.

The functions LPAD and RPAD pad their character arguments on the left and right, respectively, with a specified character (the default character is a space).

The query in Example 4-23 displays FIRST_NAME and LAST_NAME in 15-character columns, blank-padding FIRST_NAME on the left and LAST_NAME on the right.

Example 4-23 Padding Character Data

SELECT LPAD(FIRST_NAME,15) "First",
RPAD(LAST_NAME,15) "Last"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY FIRST_NAME;

Result:

First           Last
--------------- ---------------
Daniel Faviet
Ismael Sciarra
John Chen
Jose Manuel Urman
Luis Popp
Nancy Greenberg

6 rows selected.

The SUBSTR function accepts as arguments a string, a character position, and a length, and returns the substring that starts at the specified position in the string and has the specified length.

The query in Example 4-24 uses SUBSTR to abbreviate FIRST_NAME to first initial and to strip the area code from PHONE_NUMBER.

Example 4-24 Extracting Substrings from Character Data

SELECT SUBSTR(FIRST_NAME, 1, 1) || '. ' || LAST_NAME "Name",
SUBSTR(PHONE_NUMBER, 5, 8) "Phone"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

Name                         Phone
---------------------------- --------
J. Chen                      124.4269
D. Faviet                    124.4169
N. Greenberg                 124.4569
L. Popp                      124.4567
I. Sciarra                   124.4369
J. Urman                     124.4469

6 rows selected.

The REPLACE function replaces one substring with another.

The query in Example 4-25 uses the SUBSTR function in the WHERE clause to select the employees whose JOB_ID starts with 'SH', and uses the REPLACE function to replace 'SH' with 'SHIPPING' in each such JOB_ID.

Example 4-25 Replacing Substrings in Character Data

COLUMN "Job" FORMAT A15;
SELECT LAST_NAME,
REPLACE(JOB_ID, 'SH', 'SHIPPING') "Job"
FROM EMPLOYEES
WHERE SUBSTR(JOB_ID, 1, 2) = 'SH'
ORDER BY LAST_NAME;

Result:

LAST_NAME                 Job
------------------------- ---------------
Bell                      SHIPPING_CLERK
Bull                      SHIPPING_CLERK
Cabrio                    SHIPPING_CLERK
Chung                     SHIPPING_CLERK
Dellinger                 SHIPPING_CLERK
Dilly                     SHIPPING_CLERK
Everett                   SHIPPING_CLERK
Feeney                    SHIPPING_CLERK
Fleaur                    SHIPPING_CLERK
Gates                     SHIPPING_CLERK
Geoni                     SHIPPING_CLERK

LAST_NAME                 Job
------------------------- ---------------
Grant                     SHIPPING_CLERK
Jones                     SHIPPING_CLERK
McCain                    SHIPPING_CLERK
OConnell                  SHIPPING_CLERK
Perkins                   SHIPPING_CLERK
Sarchand                  SHIPPING_CLERK
Sullivan                  SHIPPING_CLERK
Taylor                    SHIPPING_CLERK
Walsh                     SHIPPING_CLERK

20 rows selected.

See Also:

Oracle Database SQL Language Reference for more information about SQL character functions

Using Datetime Functions in Queries

Datetime functions operate on date, timestamp, and interval values. Each datetime function returns a single value for each row that is evaluated. The datetime functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

To understand Example 4-26, you must understand the JOB_HISTORY table.

When an employee changes jobs, the START_DATE and END_DATE of his or her previous job are recorded in the JOB_HISTORY table. Employees who have changed jobs more than once have multiple rows in the JOB_HISTORY table, as the following query and its results show:

SELECT * FROM JOB_HISTORY
ORDER BY EMPLOYEE_ID;

Result:

EMPLOYEE_ID START_DAT END_DATE  JOB_ID     DEPARTMENT_ID
----------- --------- --------- ---------- -------------
101 21-SEP-89 27-OCT-93 AC_ACCOUNT           110
101 28-OCT-93 15-MAR-97 AC_MGR               110
102 13-JAN-93 24-JUL-98 IT_PROG               60
114 24-MAR-98 31-DEC-99 ST_CLERK              50
122 01-JAN-99 31-DEC-99 ST_CLERK              50
176 24-MAR-98 31-DEC-98 SA_REP                80
176 01-JAN-99 31-DEC-99 SA_MAN                80
200 17-SEP-87 17-JUN-93 AD_ASST               90
200 01-JUL-94 31-DEC-98 AC_ACCOUNT            90
201 17-FEB-96 19-DEC-99 MK_REP                20

10 rows selected.

The query in Example 4-26 uses the MONTHS_BETWEEN function to show how many months each employee held each of his or her previous jobs. For information about the MONTHS_BETWEEN function, see Oracle Database SQL Language Reference.

Example 4-26 Displaying the Number of Months Between Dates

SELECT e.EMPLOYEE_ID,
e.LAST_NAME,
TRUNC(MONTHS_BETWEEN(j.END_DATE, j.START_DATE)) "Months Worked"
FROM EMPLOYEES e, JOB_HISTORY j
WHERE e.EMPLOYEE_ID = j.EMPLOYEE_ID
ORDER BY "Months Worked";

Result:

EMPLOYEE_ID LAST_NAME                 Months Worked
----------- ------------------------- -------------
176 Taylor                                9
122 Kaufling                             11
176 Taylor                               11
114 Raphaely                             21
101 Kochhar                              40
201 Hartstein                            46
101 Kochhar                              49
200 Whalen                               53
102 De Haan                              66
200 Whalen                               69

10 rows selected.

The query in Example 4-27 uses the EXTRACT and SYSDATE functions to show how many years each employee in department 100 has been employed. The SYSDATE function returns the current date of the system clock. For more information about the SYSDATE function, see Oracle Database SQL Language Reference. For information about the EXTRACT function, see Oracle Database SQL Language Reference.

Example 4-27 Displaying the Number of Years Between Dates

SELECT LAST_NAME,
(EXTRACT(YEAR FROM SYSDATE) - EXTRACT(YEAR FROM HIRE_DATE)) "Years Employed"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY "Years Employed";

Result:

LAST_NAME                 Years Employed
------------------------- --------------
Popp                                   9
Urman                                 10
Chen                                  11
Sciarra                               11
Greenberg                             14
Faviet                                14

6 rows selected.

Suppose that an employee receives his or her first check on the last day of the month in which he or she was hired. The query in Example 4-28 uses the LAST_DAY function to show the first pay day for each employee in department 100. For information about the LAST_DAY function, see Oracle Database SQL Language Reference.

Example 4-28 Displaying the Last Day of a Selected Month

SELECT LAST_NAME,
HIRE_DATE "Hired",
LAST_DAY(HIRE_DATE) "Paid"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY HIRE_DATE;

Result:

LAST_NAME                 Hired     Paid
------------------------- --------- ---------
Faviet                    16-AUG-94 31-AUG-94
Greenberg                 17-AUG-94 31-AUG-94
Chen                      28-SEP-97 30-SEP-97
Sciarra                   30-SEP-97 30-SEP-97
Urman                     07-MAR-98 31-MAR-98
Popp                      07-DEC-99 31-DEC-99

6 rows selected.

Suppose that an employee receives his or her first evaluation six months after being hired. The query in Example 4-29 uses the ADD_MONTHS function to show the first evaluation day for each employee in department 100. For information about the ADD_MONTHS function, see Oracle Database SQL Language Reference.

Example 4-29 Displaying a Date Six Months from a Selected Date

SELECT LAST_NAME,
HIRE_DATE "Hired",
ADD_MONTHS(HIRE_DATE, 6) "Evaluated"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY HIRE_DATE;

Result:

LAST_NAME                 Hired     Evaluated
------------------------- --------- ---------
Faviet                    16-AUG-94 16-FEB-95
Greenberg                 17-AUG-94 17-FEB-95
Chen                      28-SEP-97 28-MAR-98
Sciarra                   30-SEP-97 31-MAR-98
Urman                     07-MAR-98 07-SEP-98
Popp                      07-DEC-99 07-JUN-00

6 rows selected.

The query in Example 4-30 uses the SYSTIMESTAMP function to display the current system time and date. SYSTIMESTAMP is similar to SYSDATE, but it returns more information. For information about the SYSTIMESTAMP function, see Oracle Database SQL Language Reference.

The table in the FROM clause of the query, DUAL, is a one-row table that Oracle Database creates automatically along with the data dictionary. Select from DUAL when you want to compute a constant expression with the SELECT statement. Because DUAL has only one row, the constant is returned only once. For more information about selecting from DUAL, see Oracle Database SQL Language Reference.

Example 4-30 Displaying System Date and Time

SELECT EXTRACT(HOUR FROM SYSTIMESTAMP) || ':' ||
EXTRACT(MINUTE FROM SYSTIMESTAMP) || ':' ||
ROUND(EXTRACT(SECOND FROM SYSTIMESTAMP), 0) || ', ' ||
EXTRACT(MONTH FROM SYSTIMESTAMP) || '/' ||
EXTRACT(DAY FROM SYSTIMESTAMP) || '/' ||
EXTRACT(YEAR FROM SYSTIMESTAMP) "System Time and Date"
FROM DUAL;

Results depend on current SYSTIMESTAMP value, but have this format:

System Time and Date
-------------------------------------------------------------------
18:47:33, 6/19/2008

See Also:

Oracle Database SQL Language Reference for more information about SQL datetime functions

Using Conversion Functions in Queries

Conversion functions convert one data type to another. The conversion functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

The query in Example 4-31 uses the TO_CHAR function to convert HIRE_DATE values (which are of type DATE) to character values that have the format FMMonth DD YYYY. FM removes leading and trailing blanks from the month name. FMMonth DD YYYY is an example of a datetime format model.

Example 4-31 Converting Dates to Characters Using a Format Template

SELECT LAST_NAME,
HIRE_DATE,
TO_CHAR(HIRE_DATE, 'FMMonth DD YYYY') "Date Started"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

LAST_NAME                 HIRE_DATE Date Started
------------------------- --------- -----------------
Chen                      28-SEP-97 September 28 1997
Faviet                    16-AUG-94 August 16 1994
Greenberg                 17-AUG-94 August 17 1994
Popp                      07-DEC-99 December 7 1999
Sciarra                   30-SEP-97 September 30 1997
Urman                     07-MAR-98 March 7 1998

6 rows selected.

The query in Example 4-32 uses the TO_CHAR function to convert HIRE_DATE values to character values that have the two standard formats DS (Date Short) and DL (Date Long).

Example 4-32 Converting Dates to Characters Using Standard Formats

SELECT LAST_NAME,
TO_CHAR(HIRE_DATE, 'DS') "Short Date",
TO_CHAR(HIRE_DATE, 'DL') "Long Date"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY LAST_NAME;

Result:

LAST_NAME                 Short Date Long Date
------------------------- ---------- -----------------------------
Chen                      9/28/1997  Sunday, September 28, 1997
Faviet                    8/16/1994  Tuesday, August 16, 1994
Greenberg                 8/17/1994  Wednesday, August 17, 1994
Popp                      12/7/1999  Tuesday, December 07, 1999
Sciarra                   9/30/1997  Tuesday, September 30, 1997
Urman                     3/7/1998   Saturday, March 07, 1998

6 rows selected.

The query in Example 4-33 uses the TO_CHAR function to convert SALARY values (which are of type NUMBER) to character values that have the format $99,999.99.

Example 4-33 Converting Numbers to Characters Using a Format Template

SELECT LAST_NAME,
TO_CHAR(SALARY, '$99,999.99') "Salary"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY SALARY;

Result:

LAST_NAME                 Salary
------------------------- -----------
Popp                        $6,900.00
Sciarra                     $7,700.00
Urman                       $7,800.00
Chen                        $8,200.00
Faviet                      $9,000.00
Greenberg                  $12,000.00

6 rows selected.

The query in Example 4-34 uses the TO_NUMBER function to convert POSTAL_CODE values (which are of type VARCHAR2) to values of type NUMBER, which it uses in calculations.

Example 4-34 Converting Characters to Numbers

SELECT CITY,
POSTAL_CODE "Old Code",
TO_NUMBER(POSTAL_CODE) + 1 "New Code"
FROM LOCATIONS
WHERE COUNTRY_ID = 'US'
ORDER BY POSTAL_CODE;

Result:

CITY                           Old Code       New Code
------------------------------ ------------ ----------
Southlake                      26192             26193
South Brunswick                50090             50091
Seattle                        98199             98200
South San Francisco            99236             99237

4 rows selected.

The query in Example 4-35 uses the TO_DATE function to convert a string of characters whose format is Month dd, YYYY, HH:MI A.M. to a DATE value.

Example 4-35 Converting a Character String to a Date

SELECT TO_DATE('January 5, 2007, 8:43 A.M.',
'Month dd, YYYY, HH:MI A.M.') "Date"
FROM DUAL;

Result:

Date
---------
05-JAN-07

The query in Example 4-36 uses the TO_TIMESTAMP function to convert a string of characters whose format is DD-Mon-RR HH24:MI:SS.FF to a TIMESTAMP value.

Example 4-36 Converting a Character String to a Time Stamp

SELECT TO_TIMESTAMP('May 5, 2007, 8:43 A.M.',
'Month dd, YYYY, HH:MI A.M.') "Timestamp"
FROM DUAL;

Result:

Timestamp
------------------------------------------------------------------------------
05-MAY-07 08.43.00.000000000 AM

See Also:

- Oracle Database SQL Language Reference for more information about SQL conversion functions

- Oracle Database SQL Language Reference for more information about the TO_CHAR function

- Oracle Database SQL Language Reference for more information about the TO_NUMBER function

- Oracle Database SQL Language Reference for more information about the TO_DATE function

- Oracle Database SQL Language Reference for more information about the TO_TIMESTAMP function

- "About the NLS_DATE_FORMAT Parameter"

Using Aggregate Functions in Queries

An aggregate function returns a single result row, based on a group of rows. The group of rows can be an entire table or view. The aggregate functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

Aggregate functions are especially powerful when used with the GROUP BY clause, which groups query results by one or more columns, with a result for each group.

The query in Example 4-37 uses the COUNT function and the GROUP BY clause to show how many people report to each manager. The wildcard character, *, represents an entire record.

Example 4-37 Counting the Number of Rows in Each Group

SELECT MANAGER_ID "Manager",
COUNT(*) "Number of Reports"
FROM EMPLOYEES
GROUP BY MANAGER_ID;

Result:

Manager Number of Reports
---------- -----------------
100                14
1
123                 8
120                 8
121                 8
147                 6
205                 1
108                 5
148                 6
149                 6
201                 1

Manager Number of Reports
---------- -----------------
102                 1
101                 5
114                 5
124                 8
145                 6
146                 6
103                 4
122                 8

19 rows selected.

Example 4-37 shows that one employee does not report to a manager. The following query selects the first name, last name, and job title of that employee:

COLUMN FIRST_NAME FORMAT A10;
COLUMN LAST_NAME FORMAT A10;
COLUMN JOB_TITLE FORMAT A10;

SELECT e.FIRST_NAME,
e.LAST_NAME,
j.JOB_TITLE
FROM EMPLOYEES e, JOBS j
WHERE e.JOB_ID = j.JOB_ID
AND MANAGER_ID IS NULL;

Result:

FIRST_NAME LAST_NAME  JOB_TITLE
---------- ---------- ----------
Steven     King       President

When used with the DISTINCT option, the COUNT function shows how many distinct values are in a data set.

The two queries in Example 4-38 show the total number of departments and the number of departments that have employees.

Example 4-38 Counting the Number of Distinct Values in a Set

SELECT COUNT(*) FROM DEPARTMENTS;

Result:

COUNT(*)
----------
27

SELECT COUNT(DISTINCT DEPARTMENT_ID) "Number of Departments"
FROM EMPLOYEES;

Result:

Number of Departments
---------------------
11

The query in Example 4-39 uses several aggregate functions to show statistics for the salaries of each JOB_ID.

Example 4-39 Using Aggregate Functions for Statistical Information

SELECT JOB_ID,
COUNT(*) "#",
MIN(SALARY) "Minimum",
ROUND(AVG(SALARY), 0) "Average",
MEDIAN(SALARY) "Median",
MAX(SALARY) "Maximum",
ROUND(STDDEV(SALARY)) "Std Dev"
FROM EMPLOYEES
GROUP BY JOB_ID
ORDER BY JOB_ID;

Result:

JOB_ID              #    Minimum    Average     Median    Maximum    Std Dev
---------- ---------- ---------- ---------- ---------- ---------- ----------
AC_ACCOUNT          1       8300       8300       8300       8300          0
AC_MGR              1      12000      12000      12000      12000          0
AD_ASST             1       4400       4400       4400       4400          0
AD_PRES             1      24000      24000      24000      24000          0
AD_VP               2      17000      17000      17000      17000          0
FI_ACCOUNT          5       6900       7920       7800       9000        766
FI_MGR              1      12000      12000      12000      12000          0
HR_REP              1       6500       6500       6500       6500          0
IT_PROG             5       4200       5760       4800       9000       1926
MK_MAN              1      13000      13000      13000      13000          0
MK_REP              1       6000       6000       6000       6000          0

JOB_ID              #    Minimum    Average     Median    Maximum    Std Dev
---------- ---------- ---------- ---------- ---------- ---------- ----------
PR_REP              1      10000      10000      10000      10000          0
PU_CLERK            5       2500       2780       2800       3100        239
PU_MAN              1      11000      11000      11000      11000          0
SA_MAN              5      10500      12200      12000      14000       1525
SA_REP             30       6100       8350       8200      11500       1524
SH_CLERK           20       2500       3215       3100       4200        548
ST_CLERK           20       2100       2785       2700       3600        453
ST_MAN              5       5800       7280       7900       8200       1066

19 rows selected.

To have the query return only rows where aggregate values meet specified conditions, use the HAVING clause.

The query in Example 4-40 shows how much each department spends annually on salaries, but only for departments for which that amount exceeds $1,000,000.

Example 4-40 Limiting Aggregate Functions to Rows that Satisfy a Condition

SELECT DEPARTMENT_ID "Department",
SUM(SALARY*12) "All Salaries"
FROM EMPLOYEES
HAVING SUM(SALARY * 12) >= 1000000
GROUP BY DEPARTMENT_ID;

Result:

Department All Salaries
---------- ------------
50      1876800
80      3654000

The RANK function returns the relative ordered rank of a number, and the PERCENT_RANK function returns the percentile position of a number.

The query in Example 4-41 shows that a salary of $3,000 is the 20th highest, and is in the 42nd percentile, among all clerks.

Example 4-41 Showing the Rank and Percentile of a Number Within a Group

SELECT RANK(3000) WITHIN GROUP
(ORDER BY SALARY DESC) "Rank",
ROUND(100 * (PERCENT_RANK(3000) WITHIN GROUP
(ORDER BY SALARY DESC)), 0) "Percentile"
FROM EMPLOYEES
WHERE JOB_ID LIKE '%CLERK';

Result:

Rank Percentile
---------- ----------
20         42

The DENSE_RANK function is like the RANK function, except that the identical values have the same rank, and there are no gaps in the ranking. Using the DENSE_RANK function, $3,000 is the 12th highest salary for clerks, as Example 4-42 shows.

Example 4-42 Showing the Dense Rank of a Number Within a Group

SELECT DENSE_RANK(3000) WITHIN GROUP (ORDER BY salary DESC) "Rank"
FROM EMPLOYEES
WHERE JOB_ID LIKE '%CLERK';

Result:

Rank
----------
12

See Also:

Oracle Database SQL Language Reference for more informaton about SQL aggregate functions

Using NULL-Related Functions in Queries

The NULL-related functions facilitate the handling of NULL values. The NULL-related functions that SQL supports are listed and described in Oracle Database SQL Language Reference.

The query in Example 4-43 returns the last name and commission of the employees whose last names begin with 'B'. If an employee receives no commission (that is, if COMMISSION_PCT is NULL), the NVL function substitutes "Not Applicable" for NULL.

Example 4-43 Substituting a String for a NULL Value

SELECT LAST_NAME,
NVL(TO_CHAR(COMMISSION_PCT), 'Not Applicable') "COMMISSION"
FROM EMPLOYEES
WHERE LAST_NAME LIKE 'B%'
ORDER BY LAST_NAME;

Result:

LAST_NAME                 COMMISSION
------------------------- ----------------------------------------
Baer                      Not Applicable
Baida                     Not Applicable
Banda                     .1
Bates                     .15
Bell                      Not Applicable
Bernstein                 .25
Bissot                    Not Applicable
Bloom                     .2
Bull                      Not Applicable

9 rows selected.

The query in Example 4-44 returns the last name, salary, and income of the employees whose last names begin with 'B', using the NVL2 function: If COMMISSION_PCT is not NULL, the income is the salary plus the commission; if COMMISSION_PCT is NULL, income is only the salary.

Example 4-44 Specifying Different Expressions for NULL and Not NULL Values

SELECT LAST_NAME, SALARY,
NVL2(COMMISSION_PCT, SALARY + (SALARY * COMMISSION_PCT), SALARY) INCOME
FROM EMPLOYEES WHERE LAST_NAME LIKE 'B%'
ORDER BY LAST_NAME;

Result:

LAST_NAME                     SALARY     INCOME
------------------------- ---------- ----------
Baer                           10000      10000
Baida                           2900       2900
Banda                           6200       6882
Bates                           7300       8468
Bell                            4000       4000
Bernstein                       9500      11970
Bissot                          3300       3300
Bloom                          10000      12100
Bull                            4100       4100

9 rows selected.

See Also:

- Oracle Database SQL Language Reference for more information about the NVL function

- Oracle Database SQL Language Reference for more information about the NVL2 function

Using CASE Expressions in Queries

A CASE expression lets you use IF ... THEN ... ELSE logic in SQL statements without invoking procedures.

The query in Example 4-45 uses a CASE expression to show proposed salary increases, based on length of service.

Example 4-45 Using a CASE Expression in a Query

SELECT LAST_NAME "Name",
HIRE_DATE "Started",
SALARY "Salary",
CASE
WHEN HIRE_DATE < TO_DATE('01-Jan-90') THEN TRUNC(SALARY*1.15, 0)
WHEN HIRE_DATE < TO_DATE('01-Jan-95') THEN TRUNC(SALARY*1.10, 0)
WHEN HIRE_DATE < TO_DATE('01-Jan-00') THEN TRUNC(SALARY*1.05, 0)
ELSE SALARY
END "Proposed Salary"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 100
ORDER BY HIRE_DATE;

Result:

Name                      Started       Salary Proposed Salary
------------------------- --------- ---------- ---------------
Faviet                    16-AUG-94       9000            9900
Greenberg                 17-AUG-94      12000           13200
Chen                      28-SEP-97       8200            8610
Sciarra                   30-SEP-97       7700            8085
Urman                     07-MAR-98       7800            8190
Popp                      07-DEC-99       6900            7245

6 rows selected.

See Also:

- "Using the CASE Statement"

- Oracle Database SQL Language Reference for more information about CASE expressions

Using the DECODE Function in Queries

The DECODE function compares a value or expression to search values, and returns a result when it finds a match. If a match is not found, then DECODE returns the default value, or NULL (if a default value is not specified).

The query in Example 4-46 uses the DECODE function to show proposed salary increases for three different jobs.

Example 4-46 Using the DECODE Function in a Query

SELECT LAST_NAME, JOB_ID, SALARY,
DECODE(JOB_ID,
'PU_CLERK', SALARY * 1.10,
'SH_CLERK', SALARY * 1.15,
'ST_CLERK', SALARY * 1.20,
SALARY) "Proposed Salary"
FROM EMPLOYEES
WHERE JOB_ID LIKE '%_CLERK'
AND LAST_NAME < 'E'
ORDER BY LAST_NAME;

Result:

LAST_NAME                 JOB_ID         SALARY Proposed Salary
------------------------- ---------- ---------- ---------------
Atkinson                  ST_CLERK         2800            3360
Baida                     PU_CLERK         2900            3190
Bell                      SH_CLERK         4000            4600
Bissot                    ST_CLERK         3300            3960
Bull                      SH_CLERK         4100            4715
Cabrio                    SH_CLERK         3000            3450
Chung                     SH_CLERK         3800            4370
Colmenares                PU_CLERK         2500            2750
Davies                    ST_CLERK         3100            3720
Dellinger                 SH_CLERK         3400            3910
Dilly                     SH_CLERK         3600            4140

11 rows selected.

See Also:

Oracle Database SQL Language Reference for information about the DECODE function

5 About DML Statements and Transactions

This chapter contains the following topics:

- About Data Manipulation Language (DML) Statements

- About Transaction Control Statements

- Committing Transactions

- Rolling Back Transactions

- Setting Savepoints in Transactions

About Data Manipulation Language (DML) Statements

Data manipulation language (DML) statements access and manipulate data in existing tables.

In the SQL*Plus environment, you can enter a DML statement after the SQL> prompt.

In the SQL Developer environment, you can enter a DML statement in the SQL Worksheet. Alternatively, you can use the SQL Developer navigation frame and tools to access and manipulate data.

To see the effect of a DML statement in SQL Developer, you might have to click the Refresh icon.

The effect of a DML statement is not permanent until you commit the transaction that includes it. A transaction is a sequence of SQL statements that Oracle Database treats as a unit (it can be a single DML statement). Until a transaction is committed, it can be rolled back (undone). For more information about transactions, see "About Transaction Control Statements".

Topics:

- About the INSERT Statement

- About the UPDATE Statement

- About the DELETE Statement

See Also:

Oracle Database SQL Language Reference for more information about DML statements

About the INSERT Statement

The INSERT statement inserts rows into an existing table.

The simplest recommended form of the INSERT statement has this syntax:

INSERT INTO table_name (list_of_columns)
VALUES (list_of_values);

Every column in list_of_columns must have a valid value in the corresponding position in list_of_values. Therefore, before you insert a row into a table, you must know what columns the table has, and what their valid values are. To get this information using SQL Developer, see "Tutorial: Viewing EMPLOYEES Table Properties and Data". To get this information using SQL*Plus, use the DESCRIBE statement. For example:

DESCRIBE EMPLOYEES;

Result:

Name                                      Null?    Type
----------------------------------------- -------- ------------

EMPLOYEE_ID                               NOT NULL NUMBER(6)
FIRST_NAME                                         VARCHAR2(20)
LAST_NAME                                 NOT NULL VARCHAR2(25)
EMAIL                                     NOT NULL VARCHAR2(25)
PHONE_NUMBER                                       VARCHAR2(20)
HIRE_DATE                                 NOT NULL DATE
JOB_ID                                    NOT NULL VARCHAR2(10)
SALARY                                             NUMBER(8,2)
COMMISSION_PCT                                     NUMBER(2,2)
MANAGER_ID                                         NUMBER(6)
DEPARTMENT_ID                                      NUMBER(4)

The INSERT statement in Example 5-1 inserts a row into the EMPLOYEES table for an employee for which all column values are known.

Example 5-1 Using the INSERT Statement When All Information Is Available

INSERT INTO EMPLOYEES (
EMPLOYEE_ID,
FIRST_NAME,
LAST_NAME,
EMAIL,
PHONE_NUMBER,
HIRE_DATE,
JOB_ID,
SALARY,
COMMISSION_PCT,
MANAGER_ID,
DEPARTMENT_ID
)
VALUES (
10,              -- EMPLOYEE_ID
'George',        -- FIRST_NAME
'Gordon',        -- LAST_NAME
'GGORDON',       -- EMAIL
'650.506.2222',  -- PHONE_NUMBER
'01-JAN-07',     -- HIRE_DATE
'SA_REP',        -- JOB_ID
9000,            -- SALARY
.1,              -- COMMISSION_PCT
148,             -- MANAGER_ID
80               -- DEPARTMENT_ID
);

Result:

1 row created.

You do not need to know all column values to insert a row into a table, but you must know the values of all NOT NULL columns. If you do not know the value of a column that can be NULL, you can omit that column from list_of_columns. Its value defaults to NULL.

The INSERT statement in Example 5-2 inserts a row into the EMPLOYEES table for an employee for which all column values are known except SALARY. For now, SALARY can have the value NULL. When you know the salary, you can change it with the UPDATE statement (see Example 5-4).

Example 5-2 Using the INSERT Statement When Not All Information Is Available

INSERT INTO EMPLOYEES (
EMPLOYEE_ID,
FIRST_NAME,
LAST_NAME,
EMAIL,
PHONE_NUMBER,
HIRE_DATE,
JOB_ID,          -- Omit SALARY; its value defaults to NULL.
COMMISSION_PCT,
MANAGER_ID,
DEPARTMENT_ID
)
VALUES (
20,              -- EMPLOYEE_ID
'John',          -- FIRST_NAME
'Keats',         -- LAST_NAME
'JKEATS',        -- EMAIL
'650.506.3333',  -- PHONE_NUMBER
'01-JAN-07',     -- HIRE_DATE
'SA_REP',        -- JOB_ID
.1,              -- COMMISSION_PCT
148,             -- MANAGER_ID
80               -- DEPARTMENT_ID
);

Result:

1 row created.

The INSERT statement in Example 5-3 tries to insert a row into the EMPLOYEES table for an employee for which LAST_NAME is not known.

Example 5-3 Using the INSERT Statement Incorrectly

INSERT INTO EMPLOYEES (
EMPLOYEE_ID,
FIRST_NAME,      -- Omit LAST_NAME (error)
EMAIL,
PHONE_NUMBER,
HIRE_DATE,
JOB_ID,
COMMISSION_PCT,
MANAGER_ID,
DEPARTMENT_ID
)
VALUES (
20,              -- EMPLOYEE_ID
'John',          -- FIRST_NAME
'JOHN',          -- EMAIL
'650.506.3333',  -- PHONE_NUMBER
'01-JAN-07',     -- HIRE_DATE
'SA_REP',        -- JOB_ID
.1,              -- COMMISSION_PCT
148,             -- MANAGER_ID
80               -- DEPARTMENT_ID
);

Result:

ORA-01400: cannot insert NULL into ("HR"."EMPLOYEES"."LAST_NAME")

See Also:

- Oracle Database SQL Language Reference for information about the INSERT statement

- Oracle Database SQL Language Reference for information about data types

- "Tutorial: Adding Rows to Tables with the Insert Row Tool"

About the UPDATE Statement

The UPDATE statement updates (changes the values of) a set of existing table rows.

A simple form of the UPDATE statement has this syntax:

UPDATE table_name
SET column_name = value [, column_name = value]...
[ WHERE condition ];

Each value must be valid for its column_name. If you include the WHERE clause, the statement updates column values only in rows that satisfy condition.

The UPDATE statement in Example 5-4 updates the value of the SALARY column in the row that was inserted into the EMPLOYEES table in Example 5-2, before the salary of the employee was known.

Example 5-4 Using the UPDATE Statement to Add Data

UPDATE EMPLOYEES
SET SALARY = 8500
WHERE LAST_NAME = 'Keats';

Result:

1 row updated.

The UPDATE statement in Example 5-5 updates the commission percentage for every employee in department 80.

Example 5-5 Using the UPDATE Statement to Update Multiple Rows

UPDATE EMPLOYEES
SET COMMISSION_PCT = COMMISSION_PCT + 0.05
WHERE DEPARTMENT_ID = 80;

Result:

36 rows updated.

See Also:

- Oracle Database SQL Language Reference for information about the UPDATE statement

- Oracle Database SQL Language Reference for information about data types

- "Tutorial: Changing Data in Tables in the Data Pane"

About the DELETE Statement

The DELETE statement deletes rows from a table.

A simple form of the DELETE statement has this syntax:

DELETE FROM table_name
[ WHERE condition ];

If you include the WHERE clause, the statement deletes only rows that satisfy condition. If you omit the WHERE clause, the statement deletes all rows from the table, but the empty table still exists. To delete a table, use the DROP TABLE statement.

The DELETE statement in Example 5-6 deletes the rows inserted in Example 5-1 and Example 5-2.

Example 5-6 Using the DELETE Statement

DELETE FROM EMPLOYEES
WHERE HIRE_DATE = '01-JAN-07';

Result:

2 rows deleted.

See Also:

- Oracle Database SQL Language Reference for information about the DELETE statement

- Oracle Database SQL Language Reference for information about the DROP TABLE statement

- "Tutorial: Deleting Rows from Tables with the Delete Selected Row(s) Tool"

About Transaction Control Statements

A transaction is a sequence of one or more SQL statements that Oracle Database treats as a unit: either all of the statements are performed, or none of them are.

You need transactions to model business processes that require that several operations be performed as a unit. For example, when a manager leaves the company, a row must be inserted into the JOB_HISTORY table to show when the manager left, and for every employee who reports to that manager, the value of MANAGER_ID must be updated in the EMPLOYEES table. To model this process in an application, you must group the INSERT and UPDATE statements into a single transaction.

The basic transaction control statements are:

- SAVEPOINT, which marks a savepoint in a transaction—a point to which you can later roll back. Savepoints are optional, and a transaction can have multiple savepoints.

- COMMIT, which ends the current transaction, makes its changes permanent, erases its savepoints, and releases its locks.

- ROLLBACK, which rolls back (undoes) either the entire current transaction or only the changes made after the specified savepoint.

In the SQL*Plus environment, you can enter a transaction control statement after the SQL> prompt.

In the SQL Developer environment, you can enter a transaction control statement in the SQL Worksheet. SQL Developer also has Commit Changes and Rollback Changes icons, which are explained in "Committing Transactions" and "Rolling Back Transactions".

Caution:

If you do not explicitly commit a transaction, and the program terminates abnormally, then the database automatically rolls back the last uncommitted transaction.
Oracle recommends that you explicitly end transactions in application programs, by either committing them or rolling them back.

See Also:

- Oracle Database Concepts for more information about transaction management

- Oracle Database SQL Language Reference for more information about transaction control statements

Committing Transactions

Committing a transaction makes its changes permanent, erases its savepoints, and releases its locks.

To explicitly commit a transaction, use either the COMMIT statement or (in the SQL Developer environment) the Commit Changes icon.

Note:

Oracle Database issues an implicit COMMIT statement before and after any data definition language (DDL) statement. For information about DDL statements, see "About Data Definition Language (DDL) Statements".

Before you commit a transaction:

- Your changes are visible to you, but not to other users of the database instance.

- Your changes are not final—you can undo them with a ROLLBACK statement.

After you commit a transaction:

- Your changes are visible to other users, and to their statements that run after you commit your transaction.

- Your changes are final—you cannot undo them with a ROLLBACK statement.

Example 5-7 adds one row to the REGIONS table (a very simple transaction), checks the result, and then commits the transaction.

Example 5-7 Committing a Transaction

Before transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East and Africa

Transaction (add row to table):

INSERT INTO regions (region_id, region_name) VALUES (5, 'Africa');

Result:

1 row created.

Check that row was added:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East and Africa
5 Africa

Commit transaction:

COMMIT;

Result:

Commit complete.

See Also:

Oracle Database SQL Language Reference for information about the COMMIT statement

Rolling Back Transactions

Rolling back a transaction undoes its changes. You can roll back the entire current transaction, or you can roll it back only to a specified savepoint.

To roll back the current transaction only to a specified savepoint, you must use the ROLLBACK statement with the TO SAVEPOINT clause.

To roll back the entire current transaction, use either the ROLLBACK statement without the TO SAVEPOINT clause, or (in the SQL Developer environment) the Rollback Changes icon.

Rolling back the entire current transaction:

- Ends the transaction

- Reverses all of its changes

- Erases all of its savepoints

- Releases any transaction locks

Rolling back the current transaction only to the specified savepoint:

- Does not end the transaction

- Reverses only the changes made after the specified savepoint

- Erases only the savepoints set after the specified savepoint (excluding the specified savepoint itself)

- Releases all table and row locks acquired after the specified savepoint
Other transactions that have requested access to rows locked after the specified savepoint must continue to wait until the transaction is either committed or rolled back. Other transactions that have not requested the rows can request and access the rows immediately.

To see the effect of a rollback in SQL Developer, you might have to click the Refresh icon.

As a result of Example 5-7, the REGIONS table has a region called 'Middle East and Africa' and a region called 'Africa'. Example 5-8 corrects this problem (a very simple transaction) and checks the change, but then rolls back the transaction and checks the rollback.

Example 5-8 Rolling Back an Entire Transaction

Before transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East and Africa
5 Africa

Transaction (change table):

UPDATE REGIONS
SET REGION_NAME = 'Middle East'
WHERE REGION_NAME = 'Middle East and Africa';

Result:

1 row updated.

Check change:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East
5 Africa

Roll back transaction:

ROLLBACK;

Result:

Rollback complete.

Check rollback:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East and Africa
5 Africa

See Also:

Oracle Database SQL Language Reference for information about the ROLLBACK statement

Setting Savepoints in Transactions

The SAVEPOINT statement marks a savepoint in a transaction—a point to which you can later roll back. Savepoints are optional, and a transaction can have multiple savepoints.

Example 5-9 does a transaction that includes several DML statements and several savepoints, and then rolls back the transaction to one savepoint, undoing only the changes made after that savepoint.

Example 5-9 Rolling Back a Transaction to a Savepoint

Check REGIONS table before transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East and Africa
5 Africa

5 rows selected.

Check countries in region 4 before transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          4
Israel                                   IL          4
Kuwait                                   KW          4
Nigeria                                  NG          4
Zambia                                   ZM          4
Zimbabwe                                 ZW          4

6 rows selected.

Check countries in region 5 before transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

no rows selected

Transaction, with several savepoints:

UPDATE REGIONS
SET REGION_NAME = 'Middle East'
WHERE REGION_NAME = 'Middle East and Africa';

UPDATE COUNTRIES
SET REGION_ID = 5
WHERE COUNTRY_ID = 'ZM';
SAVEPOINT zambia;

UPDATE COUNTRIES
SET REGION_ID = 5
WHERE COUNTRY_ID = 'NG';
SAVEPOINT nigeria;

UPDATE COUNTRIES
SET REGION_ID = 5
WHERE COUNTRY_ID = 'ZW';
SAVEPOINT zimbabwe;

UPDATE COUNTRIES
SET REGION_ID = 5
WHERE COUNTRY_ID = 'EG';
SAVEPOINT egypt;

Check REGIONS table after transaction:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East
5 Africa

5 rows selected.

Check countries in region 4 after transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Israel                                   IL          4
Kuwait                                   KW          4

2 rows selected.

Check countries in region 5 after transaction:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          5
Nigeria                                  NG          5
Zambia                                   ZM          5
Zimbabwe                                 ZW          5

4 rows selected.

ROLLBACK TO SAVEPOINT nigeria;

Check REGIONS table after rollback:

SELECT * FROM REGIONS
ORDER BY REGION_ID;

Result:

REGION_ID REGION_NAME
---------- -------------------------
1 Europe
2 Americas
3 Asia
4 Middle East
5 Africa

5 rows selected.

Check countries in region 4 after rollback:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 4
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Egypt                                    EG          4
Israel                                   IL          4
Kuwait                                   KW          4
Zimbabwe                                 ZW          4

4 rows selected.

Check countries in region 5 after rollback:

SELECT COUNTRY_NAME, COUNTRY_ID, REGION_ID
FROM COUNTRIES
WHERE REGION_ID = 5
ORDER BY COUNTRY_NAME;

Result:

COUNTRY_NAME                             CO  REGION_ID
---------------------------------------- -- ----------
Nigeria                                  NG          5
Zambia                                   ZM          5

2 rows selected.

See Also:

Oracle Database SQL Language Reference for information about the SAVEPOINT statement

6 Creating and Managing Schema Objects

This chapter contains the following topics:

- About Data Definition Language (DDL) Statements

- About Schema Object Names

- Creating and Managing Tables

- Creating and Managing Views

- Creating and Managing Sequences

- Creating and Managing Synonyms

About Data Definition Language (DDL) Statements

The statements that create, change, and drop schema objects are data definition language (DDL) statements. Before and after a DDL statement, Oracle Database issues an implicit COMMIT statement; therefore, you cannot roll back a DDL statement.

In the SQL*Plus environment, you can enter a DDL statement after the SQL> prompt.

In the SQL Developer environment, you can enter a DDL statement in the SQL Worksheet. Alternatively, you can use SQL Developer tools to create, change, and drop objects.

Some DDL statements that create schema objects have an optional OR REPLACE clause, which allows a statement to replace an existing schema object with another that has the same name and type. When SQL Developer generates code for one of these statements, it always includes the OR REPLACE clause.

To see the effect of a DDL statement in SQL Developer, you might have to click the Refresh icon.

See Also:

- Oracle Database SQL Language Reference for more information about DDL statements

- "Committing Transactions"

About Schema Object Names

When creating schema objects, you must observe the schema object naming rules in Oracle Database SQL Language Reference.

Tip:

Use the same prefix for names of objects of the same type. For example, t_ for tables, v_ for views, seq_ for sequences, and syn_ for synonyms. This practice makes your objects easy to identify, and groups them in the SQL Developer Connections navigator display, SQL Developer reports, and queries whose results are ordered by object name.

Creating and Managing Tables

Tables are the basic units of data storage in Oracle Database. Tables hold all user-accessible data. Each table contains rows that represent individual data records. Rows are composed of columns that represent the fields of the records.

Topics:

- About SQL Data Types

- Creating Tables

- Ensuring Data Integrity in Tables

- Tutorial: Adding Rows to Tables with the Insert Row Tool

- Tutorial: Changing Data in Tables in the Data Pane

- Tutorial: Deleting Rows from Tables with the Delete Selected Row(s) Tool

- Managing Indexes

- Dropping Tables

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

See Also:

- "Tutorial: Viewing EMPLOYEES Table Properties and Data"

- Oracle Database Concepts for general information about tables

About SQL Data Types

When you create a table, you must specify the SQL data type for each column. The data type of a column determines what values the column can contain. For example, a column of type DATE can contain the value '01-MAY-05', but it cannot contain the numeric value 2 or the character value 'shoe'. SQL data types fall into two categories: built-in and user-defined. (PL/SQL has additional data types—see "About PL/SQL Data Types".)

See Also:

- Oracle Database SQL Language Reference for a summary of built-in SQL data types

- Oracle Database Concepts for introductions to each of the built-in SQL data types

- Oracle Database SQL Language Reference for more information about user-defined data types

- "About PL/SQL Data Types"

Creating Tables

To create tables, use either the SQL Developer tool Create Table or the DDL statement CREATE TABLE. This topic shows how to use both of these ways to create these tables, which will contain data about employee evaluations:

- PERFORMANCE_PARTS, which contains the categories of employee performance that are evaluated and their relative weights

- EVALUATIONS, which contains employee information, evaluation date, job, manager, and department

- SCORES, which contains the scores assigned to each performance category for each evaluation

These tables are part of the sample application that the tutorials and examples in this document show how to develop and deploy.

Topics:

- Tutorial: Creating a Table with the Create Table Tool

- Creating Tables with the CREATE TABLE Statement

Tutorial: Creating a Table with the Create Table Tool

This tutorial shows how to create the PERFORMANCE_PARTS table using the Create Table tool.

To create the PERFORMANCE_PARTS table using the Create Table tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Tables.
A list of choices appears.

3. Click New Table.
The Create Table window opens, with default values for a new table, which has only one row.

4. For Schema, accept the default value, HR.

5. For Name, enter PERFORMANCE_PARTS.

6. In the default row:

- For Column Name, enter PERFORMANCE_ID.

- For Type, accept the default value, VARCHAR2.

- For Size, enter 2.

- For Not Null and Primary Key, accept the default values, deselected.

7. Click Add Column.

8. For Column Name, enter NAME.

9. For Type, enter VARCHAR2.

10. For Size, enter 80.

11. Click Add Column.

12. For Column Name, enter WEIGHT.

13. For Type, enter NUMBER.

14. Click OK.
The table PERFORMANCE_PARTS is created. To see it, expand Tables in the navigation frame.

See Also:

Oracle Database SQL Developer User's Guide for more information about using SQL Developer to create tables

Creating Tables with the CREATE TABLE Statement

This topic shows how to use the CREATE TABLE statement to create the EVALUATIONS and SCORES tables.

The CREATE TABLE statement in Example 6-1 creates the EVALUATIONS table.

Example 6-1 Creating the EVALUATIONS Table with CREATE TABLE

CREATE TABLE EVALUATIONS (
EVALUATION_ID    NUMBER(8,0),
EMPLOYEE_ID      NUMBER(6,0),
EVALUATION_DATE  DATE,
JOB_ID           VARCHAR2(10),
MANAGER_ID       NUMBER(6,0),
DEPARTMENT_ID    NUMBER(4,0),
TOTAL_SCORE      NUMBER(3,0)
);

Result:

Table created.

The CREATE TABLE statement in Example 6-2 creates the SCORES table.

Example 6-2 Creating the SCORES Table with CREATE TABLE

CREATE TABLE SCORES (
EVALUATION_ID   NUMBER(8,0),
PERFORMANCE_ID  VARCHAR2(2),
SCORE           NUMBER(1,0)
);

Result:

Table created.

In SQL Developer, in the navigation frame, if you expand Tables, you can see the tables EVALUATIONS and SCORES.

If you select a table in the navigation frame, and then click the tab SQL in the right frame, the SQL pane shows the SQL statement that created the table.

See Also:

Oracle Database SQL Language Reference for information about the CREATE TABLE statement

Ensuring Data Integrity in Tables

To ensure that the data in your tables satisfies the business rules that your application models, you can use constraints, application logic, or both.

Constraints restrict the values that columns can have. Trying to change the data in a way that violates a constraint causes an error and rolls back the change. Trying to add a constraint to a populated table causes an error if existing data violates the constraint.

Tip:

Wherever possible, use constraints instead of application logic. Oracle Database checks that all data obeys constraints much faster than application logic can.

Constraints can be enabled and disabled. By default, they are created in the enabled state.

Topics:

- About Constraint Types

- Tutorial: Adding Constraints to Existing Tables

See Also:

- Oracle Database Concepts for additional general information about constraints

- Oracle Database SQL Language Reference for syntactic information about constraints

- "Installing the Sample Application"

About Constraint Types

The constraint types are:

- Not Null, which prevents a value from being null
In the EMPLOYEES table, the column LAST_NAME has the NOT NULL constraint, which enforces the business rule that every employee must have a last name.

- Unique, which prevents multiple rows from having the same value in the same column or combination of columns, but allows some values to be null
In the EMPLOYEES table, the column EMAIL has the UNIQUE constraint, which enforces the business rule that an employee can have no email address, but cannot have the same email address as another employee.

- Primary Key, which is a combination of NOT NULL and UNIQUE
In the EMPLOYEES table, the column EMPLOYEE_ID has the PRIMARY KEY constraint, which enforces the business rule that every employee must have a unique employee identification number.

- Foreign Key, which requires values in one table to match values in another table
In the EMPLOYEES table, the column JOB_ID has a FOREIGN KEY constraint that references the JOBS table, which enforces the business rule that an employee cannot have a JOB_ID that is not in the JOBS table.

- Check, which requires that a value satisfy a specified condition
The EMPLOYEES table does not have CHECK constraints. However, suppose that EMPLOYEES needs a new column, EMPLOYEE_AGE, and that every employee must be at least 18. The constraint CHECK (EMPLOYEE_AGE >= 18) enforces the business rule.

Tip:

Use check constraints only when other constraint types cannot provide the necessary checking.

- REF, which further describes the relationship between the column and the object that it references
For information about REF constraints, see Oracle Database Concepts.

See Also:

- Oracle Database Concepts for additional general information about constraint types

- Oracle Database SQL Language Reference for syntactic information about constraints

Tutorial: Adding Constraints to Existing Tables

To add constraints to existing tables, use either SQL Developer tools or the DDL statement ALTER TABLE. This topic shows how to use both of these ways to add constraints to the tables created in "Creating Tables".

This tutorial has several procedures. The first procedure (immediately after this paragraph) uses the Edit Table tool to add a Not Null constraint to the NAMES column of the PERFORMANCE_PARTS table. The remaining procedures show how to use other tools to add constraints; however, you could add the same constraints using the Edit Table tool.

Note:

After any step of the tutorial, you can view the constraints that a table has:

1. In the navigation frame, select the name of the table.

2. In the right frame, click the tab Constraints.

For more information about viewing table properties and data, see "Tutorial: Viewing EMPLOYEES Table Properties and Data".

To add a Not Null constraint using the Edit Table tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click PERFORMANCE_PARTS.
A list of choices appears.

4. Click Edit.
The Edit Table window opens. By default, Columns is selected, the columns of the PERFORMANCE_PARTS table are listed, the column PERFORMANCE_ID is selected, and its properties are listed.

5. Click the column NAME.
The properties of the column NAME appear. The property "Cannot be NULL" is deselected.

6. Select Cannot be NULL.

7. Click OK.
The Not Null constraint is added to the NAME column of the PERFORMANCE_PARTS table.

The following procedure uses the ALTER TABLE statement to add a Not Null constraint to the WEIGHT column of the PERFORMANCE_PARTS table.

To add a Not Null constraint using the ALTER TABLE statement:

1. Click the icon SQL Worksheet.
The SQL Worksheet pane appears.

2. In the SQL Worksheet pane, type this statement:

ALTER TABLE PERFORMANCE_PARTS
MODIFY WEIGHT NOT NULL;

3. Click the icon Execute Statement.
The statement runs, adding the Not Null constraint to the WEIGHT column of the PERFORMANCE_PARTS table.

The following procedure uses the Add Unique tool to add a Unique constraint to the SCORES table.

To add a Unique constraint using the Add Unique tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click SCORES.
A list of choices appears.

4. Click Constraint.
A list of choices appears.

5. Click Add Unique.
The Add Unique window opens.

6. For Constraint Name, enter SCORES_EVAL_PERF_UNIQUE.

7. For Column 1, select EVALUATION_ID from the drop-down menu.

8. For Column 2, select PERFORMANCE_ID from the drop-down menu.

9. Click Apply.
The Confirmation window opens.

10. Click OK.
A unique constraint named SCORES_EVAL_PERF_UNIQUE is added to the SCORES table.

The following procedure uses the Add Primary Key tool to add a Primary Key constraint to the PERFORMANCE_ID column of the PERFORMANCE_PARTS table.

To add a Primary Key constraint using the Add Primary Key tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click PERFORMANCE_PARTS.
A list of choices appears.

4. Click Constraint.
A list of choices appears.

5. Click Add Primary Key.
The Add Primary Key window opens.

6. For Primary Key Name, enter PERF_PERF_ID_PK.

7. For Column 1, select PERFORMANCE_ID from the drop-down menu.

8. Click Apply.
The Confirmation window opens.

9. Click OK.
A primary key constraint named PERF_PERF_ID_PK is added to the PERFORMANCE_ID column of the PERFORMANCE_PARTS table.

The following procedure uses the ALTER TABLE statement to add a Primary Key constraint to the EVALUATION_ID column of the EVALUATIONS table.

To add a Primary Key constraint using the ALTER TABLE statement:

1. Click the icon SQL Worksheet.
The SQL Worksheet pane appears. Under "Enter SQL Statement:" is a field where you can enter a SQL statement.

2. In the SQL Worksheet pane, type this statement:

ALTER TABLE EVALUATIONS
ADD CONSTRAINT EVAL_EVAL_ID_PK PRIMARY KEY (EVALUATION_ID);

3. Click the icon Execute Statement.
The statement runs, adding the Primary Key constraint to the EVALUATION_ID column of the EVALUATIONS table.

The following procedure uses the Add Foreign Key tool to add two Foreign Key constraints to the SCORES table.

To add two Foreign Key constraints using the Add Foreign Key tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click SCORES.
A list of choices appears.

4. Click Constraint.
A list of choices appears.

5. Click Add Foreign Key.
The Add Foreign Key window opens.

6. For Foreign Key Name, enter SCORES_EVAL_FK.

7. For Column Name, select EVALUATION_ID from the drop-down menu.

8. For Reference Table Name, select EVALUATIONS from the drop-down menu.

9. For Referencing Column, select EVALUATION_ID from the drop-down menu.

10. Click Apply.
The Confirmation window opens.

11. Click OK.
A foreign key constraint named SCORES_EVAL_FK is added to the EVALUTION_ID column of the SCORES table, referencing the EVALUTION_ID column of the EVALUATIONS table.

The following steps add another foreign key constraint to the SCORES table.

12. Right-click SCORES.
A list of tables appears.

13. Click Constraint.
A list of choices appears.

14. Click Add Foreign Key.
The Add Foreign Key window opens.

15. For Foreign Key Name, enter SCORES_PERF_FK.

16. For Column Name, select PERFORMANCE_ID from the drop-down menu.

17. For Reference Table Name, select PERFORMANCE_PARTS from the drop-down menu.

18. For Referencing Column, select PERFORMANCE_ID from the drop-down menu.

19. Click Apply.
The Confirmation window opens.

20. Click OK.
A foreign key constraint named SCORES_PERF_FK is added to the EVALUTION_ID column of the SCORES table, referencing the EVALUTION_ID column of the EVALUATIONS table.

The following procedure uses the ALTER TABLE statement to add a Foreign Key constraint to the EMPLOYEE_ID column of the EVALUATIONS table, referencing the EMPLOYEE_ID column of the EMPLOYEES table.

To add a Foreign Key constraint using the ALTER TABLE statement:

1. Click the icon SQL Worksheet.
The SQL Worksheet pane appears. Under "Enter SQL Statement:" is a field where you can enter a SQL statement.

2. In the SQL Worksheet pane, type this statement:

ALTER TABLE EVALUATIONS
ADD CONSTRAINT EVAL_EMP_ID_FK FOREIGN KEY (EMPLOYEE_ID)
REFERENCES EMPLOYEES (EMPLOYEE_ID);

3. Click the icon Execute Statement.
The statement runs, adding the Foreign Key constraint to the EMPLOYEE_ID column of the EVALUATIONS table, referencing the EMPLOYEE_ID column of the EMPLOYEES table.

The following procedure uses the Add Check tool to add a Check constraint to the SCORES table.

To add a Check constraint using the Add Check tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click SCORES.
A list of choices appears.

4. Click Constraint.
A list of choices appears.

5. Click Add Check.
The Add Check window opens.

6. For Constraint Name, enter SCORE_VALID.

7. For Check Condition, enter score >= 0 and score <= 9.

8. For Status, accept the default, ENABLE.

9. Click Apply.
The Confirmation window opens.

10. Click OK.
A Check constraint named SCORE_VALID is added to the SCORES table.

See Also:

- Oracle Database SQL Language Reference for more information about the ALTER TABLE statement

- Oracle Database SQL Developer User's Guide for information about adding constraints to a table when you create it with SQL Developer

- Oracle Database SQL Language Reference for information about adding constraints to a table when you create it with the CREATE TABLE statement

Tutorial: Adding Rows to Tables with the Insert Row Tool

This tutorial shows how to use the Insert Row tool to add six populated rows to the PERFORMANCE_PARTS table (created in "Tutorial: Creating a Table with the Create Table Tool").

To add rows to the PERFORMANCE_PARTS table using the Insert Row tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Select PERFORMANCE_PARTS.

4. In the right frame, click the tab Data.
The Data pane appears, showing the names of the columns of the PERFORMANCE_PARTS table and no rows.

5. In the Data pane, click the icon Insert Row.

A new row appears, with empty columns.

6. Click the cell under the column heading PERFORMANCE_ID.

7. Type WM.

The value of PERFORMANCE_ID is now WM.

8. Either press the key Tab or click the cell under the column heading NAME.

9. Type Workload Management.

The value of NAME is now Workload Management.

10. Either press the key Tab or click the cell under the column heading WEIGHT.

11. Type 0.2.

12. Press the key Enter.

The value of WEIGHT is now 0.2.

13. Add and populate a second row by repeating steps 5 through 12 with these values:

- For PERFORMANCE_ID, type BR.

- For NAME, type Building Relationships.

- For WEIGHT, type 0.2.

14. Add and populate a third row by repeating steps 5 through 12 with these values:

- For PERFORMANCE_ID, type CF.

- For NAME, type Customer Focus.

- For WEIGHT, type 0.2.

15. Add and populate a fourth row by repeating steps 5 through 12 with these values:

- For PERFORMANCE_ID, type CM.

- For NAME, type Communication.

- For WEIGHT, type 0.2.

16. Add and populate a fifth row by repeating steps 5 through 12 with these values:

- For PERFORMANCE_ID, type TW.

- For NAME, type Teamwork.

- For WEIGHT, type 0.2.

17. Add and populate a sixth row by repeating steps 5 through 12, using these values:

- For PERFORMANCE_ID, type RO.

- For NAME, type Results Orientation.

- For WEIGHT, type 0.2.

18. Click the icon Commit Changes.
Under the Data pane is the Data Editor Log pane.

19. Check the Data Editor Log pane for the message "Commit Successful".

20. Check the new rows in the Data Pane.

See Also:

"About the INSERT Statement"

Tutorial: Changing Data in Tables in the Data Pane

This tutorial shows how to change three of the WEIGHT values in the PERFORMANCE_PARTS table (populated in "Tutorial: Adding Rows to Tables with the Insert Row Tool") in the Data pane.

To change data in the PERFORMANCE_PARTS table using the Data pane:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Select PERFORMANCE_PARTS.

4. In the right frame, click the tab Data.
The Data pane appears, showing the rows of the PERFORMANCE_PARTS table.

5. In the row where NAME is Workload Management:

1. Click the WEIGHT value.

2. Enter the value 0.3.

3. Press the key Enter.

6. In the row where NAME is Building Relationships:

1. Click the WEIGHT value.

2. Enter the value 0.15.

3. Press the key Enter.

7. In the row where NAME is Customer Focus:

1. Click the WEIGHT value.

2. Enter the value 0.15.

3. Press the key Enter.

8. Click the icon Commit Changes.
This icon is a picture of a data drum with a green check mark in the lower right corner.

Under the Data pane is the Data Editor Log pane.

9. Check the Data Editor Log pane for the message "Commit Successful".

10. Check the new data in the Data Pane.

See Also:

"About the UPDATE Statement"

Tutorial: Deleting Rows from Tables with the Delete Selected Row(s) Tool

This tutorial shows how to use the Delete Selected Row(s) tool to delete a row from the PERFORMANCE_PARTS table (populated in "Tutorial: Adding Rows to Tables with the Insert Row Tool").

To delete row from PERFORMANCE_PARTS using Delete Selected Row(s) tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Select PERFORMANCE_PARTS.

4. In the right frame, click the tab Data.
The Data pane appears, showing the rows of the PERFORMANCE_PARTS table.

5. Click the row where NAME is Results Orientation.

6. Click the icon Delete Selected Row(s).

7. Click the icon Commit Changes.
The row is deleted.

Under the Data pane is the Data Editor - Log pane.

8. Check the Data Editor Log pane for the message "Commit Successful".

Note:

If you delete every row of a table, the empty table still exists. To delete a table, see "Dropping Tables".

See Also:

"About the DELETE Statement"

Managing Indexes

You can create indexes on one or more columns of a table to speed SQL statement execution on that table. When properly used, indexes are the primary means of reducing disk I/O.

When you define a primary key on a table, Oracle Database creates a Unique index on the primary key. For example, in "Tutorial: Adding Constraints to Existing Tables", you added a Primary Key constraint to the EVALUATION_ID column of the EVALUATIONS table. Therefore, if you select the EVALUATIONS table in the SQL Developer navigation frame and click the Indexes tab, the Indexes pane shows a Unique index on the EVALUATION_ID column.

Topics:

- Tutorial: Adding an Index with the Create Index Tool

- Tutorial: Changing an Index with the Edit Index Tool

- Tutorial: Dropping an Index

See Also:

For more information about indexes:

- Oracle Database Concepts

- Oracle Database Advanced Application Developer's Guide

Tutorial: Adding an Index with the Create Index Tool

To create an index, use either the SQL Developer tool Create Index or the DDL statement CREATE INDEX.

This tutorial shows how to use the Create Index tool to add an index to the EVALUATIONS table (created in "Creating Tables with the CREATE TABLE Statement"). The equivalent DDL statement is:

CREATE INDEX EVAL_JOB_IX
ON EVALUATIONS (JOB_ID ASC) NOPARALLEL;

To add an index to the EVALUATIONS table using the Create Index tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears, including EVALUATIONS.

3. Right-click EVALUATIONS.
A list of choices appears.

4. Select Index.
A list of choices appears.

5. Select Create Index.
The Create Index window opens.

6. For Schema, accept the default, HR.

7. For Name, type EVAL_JOB_IX.

8. Select the tab Definition.
The Definition pane shows the default values for index properties.

9. In the field labeled "Column Name or Expression:", type JOB_ID.
(For all other properties, accept the default values.)

10. Click OK.
Now the EVALUATIONS table has an index named EVAL_JOB_IX on the column JOB_ID.

See Also:

Oracle Database SQL Language Reference for information about the CREATE INDEX statement

Tutorial: Changing an Index with the Edit Index Tool

To change an index, use either the SQL Developer tool Edit Index or the DDL statements DROP INDEX and CREATE INDEX.

This tutorial shows how to use the Edit Index tool to reverse the sort order of the index EVAL_JOB_IX (created in "Tutorial: Adding an Index with the Create Index Tool"). The equivalent DDL statements are:

DROP INDEX EVAL_JOB_ID;

CREATE INDEX EVAL_JOB_IX
ON EVALUATIONS (JOB_ID DESC) NOPARALLEL;

To reverse the sort order of the index EVAL_JOB_IX using the Edit Index tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Indexes.
A list of indexes appears, including EVAL_JOB_IX.

3. Right-click EVAL_JOB_IX.
A list of choices appears.

4. Click Edit.
A list of choices appears.

5. Click Edit Index.
The Edit Index window opens.

6. In the Edit Index window, change Order to DESC.

7. Click OK.

See Also:

Oracle Database SQL Language Reference for information about the ALTER INDEX statement

Tutorial: Dropping an Index

To drop an index, use either the SQL Developer tool Drop or the DDL statement DROP INDEX.

This tutorial shows how to use the navigation frame and Drop tool to drop the index EVAL_JOB_IX (created in "Tutorial: Adding an Index with the Create Index Tool"). The equivalent DDL statement is:

DROP INDEX EVAL_JOB_ID;

To drop the index EVAL_JOB_IX:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Indexes.
A list of indexes appears, including EVAL_JOB_IX.

3. Right-click EVAL_JOB_IX.
A list of choices appears.

4. Click Drop.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

Oracle Database SQL Language Reference for information about the DROP INDEX statement

Dropping Tables

To drop a table, use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP TABLE.

Caution:

Do not drop any of the tables that you created in "Creating Tables"—you need them for later tutorials. If you want to practice dropping tables, create simple ones and then drop them.

To drop a table using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Tables.
A list of tables appears.

3. Right-click the name of the table to drop.
A list of choices appears.

4. Click Table.
A list of choices appears.

5. Click Drop.
The Drop window opens.

6. Click Apply.
The Confirmation window opens.

7. Click OK.

See Also:

Oracle Database SQL Language Reference for information about the DROP TABLE statement

Creating and Managing Views

A view presents the output of a query as a table. In most places that you can use a table, you can use a view. Views are useful when you need frequent access to information that is stored in several different tables.

Topics:

- Creating Views

- Tutorial: Changing Views with the Edit View and Rename Tools

- Dropping Views

See Also:

- Chapter 4, "Selecting Table Data," for information about queries

- Oracle Database Concepts for additional general information about views

Creating Views

To create views, use either the SQL Developer tool Create View or the DDL statement CREATE VIEW. This topic shows how to use both of these ways to create these views:

- SALESFORCE, which contains the names and salaries of the employees in the Sales department

- EMP_LOCATIONS, which contains the names and locations of all employees

These view are part of the sample application that the tutorials and examples in this document show how to develop and deploy.

Topics:

- Tutorial: Creating a View with the Create View Tool

- Creating Views with the CREATE VIEW Statement

See Also:

- Oracle Database SQL Developer User's Guide for more information about using SQL Developer to create a view

- Oracle Database SQL Language Reference for more information about the CREATE VIEW statement

Tutorial: Creating a View with the Create View Tool

This tutorial shows how to create the SALESFORCE view using the Create View tool.

To create the SALESFORCE view using the Create View tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Views.
A list of choices appears.

3. Click New View.
The Create View window opens, with default values for a new view.

4. For Schema, accept the default value, HR.

5. For Name, enter SALESFORCE.

6. Click the tab SQL Query.
The SQL Query pane appears.

7. In the SQL Query field:

- After SELECT, type:

FIRST_NAME || ' ' || LAST_NAME "Name", SALARY*12 "Annual Salary"

- After FROM, type:

EMPLOYEES WHERE DEPARTMENT_ID = 80

8. Click Test Syntax.
A message appears in the field SQL Parse Results.

9. If the message is not "No errors found in SQL", return to step 7 and correct the syntax errors in the query.

10. Click OK.
The view SALESFORCE is created. To see it, expand Views in the navigation frame.

See Also:

Oracle Database SQL Developer User's Guide for more information about using SQL Developer to create views

Creating Views with the CREATE VIEW Statement

The CREATE VIEW statement in Example 6-3 creates the EMP_LOCATIONS view, which joins four tables. (For information about joins, see Selecting Data from Multiple Tables.)

Example 6-3 Creating the EMP_LOCATIONS View with CREATE VIEW

CREATE VIEW EMP_LOCATIONS AS
SELECT e.EMPLOYEE_ID,
e.LAST_NAME || ', ' || e.FIRST_NAME NAME,
d.DEPARTMENT_NAME DEPARTMENT,
l.CITY CITY,
c.COUNTRY_NAME COUNTRY
FROM EMPLOYEES e, DEPARTMENTS d, LOCATIONS l, COUNTRIES c
WHERE e.DEPARTMENT_ID = d.DEPARTMENT_ID AND
d.LOCATION_ID = l.LOCATION_ID AND
l.COUNTRY_ID = c.COUNTRY_ID
ORDER BY LAST_NAME;

Result:

View created.

See Also:

Oracle Database SQL Language Reference for information about the CREATE VIEW statement

Tutorial: Changing Views with the Edit View and Rename Tools

To change the query in a view, use either the SQL Developer tool Edit View or the DDL statement CREATE VIEW with the OR REPLACE clause. To change the name of a view, use either the Rename tool or the RENAME statement.

This tutorial shows how to use the Edit View tool to add the employees of the Marketing department to the SALESFORCE view (created in "Tutorial: Creating a View with the Create View Tool") and the and Rename tool to change its name to SALES_MARKETING. The equivalent DDL statements are:

CREATE OR REPLACE VIEW SALESFORCE AS
SELECT FIRST_NAME || ' ' || LAST_NAME "Name",
SALARY*12 "Annual Salary"
FROM EMPLOYEES
WHERE DEPARTMENT_ID = 80 OR DEPARTMENT_ID = 20;

RENAME SALESFORCE to SALES_MARKETING;

To change the SALESFORCE view using the Edit View and Rename tools:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Views.
A list of views appears.

3. Right-click SALESFORCE.
A list of choices appears.

4. Select Edit.
The Edit View window opens. Its SQL Query field contains the query to be changed.

5. Add this to the end of the query:

OR DEPARTMENT_ID = 20

6. Click Test Syntax.
A message appears in the field SQL Parse Results.

7. If the message is not "No errors found in SQL", return to step 5 and correct the syntax errors in the query.

8. Click OK.
The employees of the Marketing department are added to the SALESFORCE view. Now change the name of the view to SALES_MARKETING.

9. Right-click SALESFORCE.
A list of choices appears.

10. Select Rename.
The Rename window opens. It has a New View Name field.

11. In the New View Name field, type SALES_MARKETING.

12. Click Apply.
The Confirmation window opens.

13. Click OK.

See Also:

- Oracle Database SQL Language Reference for information about the CREATE VIEW statement with the OR REPLACE clause

- Oracle Database SQL Language Reference for information about the RENAME statement

Dropping Views

To drop a view, use either the SQL Developer navigation frame and Drop tool or the DDL statement DROP VIEW.

This tutorial shows how to use the navigation frame and Drop tool to drop the view SALES_MARKETING (changed in "Tutorial: Changing Views with the Edit View and Rename Tools"). The equivalent DDL statement is:

DROP VIEW SALES_MARKETING;

To drop the view SALES_MARKETING using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Views.
A list of views appears.

3. Right-click SALES_MARKETING.
A list of choices appears.

4. Click Drop.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

- Oracle Database SQL Language Reference for information about the DROP VIEW statement

Creating and Managing Sequences

Sequences are schema objects that generate unique sequential values, which are very useful when you need unique primary keys. The HR schema has three sequences: DEPARTMENTS_SEQ, EMPLOYEES_SEQ, and LOCATIONS_SEQ.

Sequences are used through the pseudocolumns CURRVAL and NEXTVAL, which return the current and next values of the sequence, respectively. After creating a sequence, you must initialize it by using NEXTVAL to get its first value. Only after the sequence is initialized does CURRVAL return its current value.

Tip:

When you plan to use a sequence to populate the primary key of a table, give the sequence a name that reflects this purpose. (This topic uses the naming convention table_name_SEQ.)

Topics:

- Tutorial: Creating a Sequence

- Dropping Sequences

See Also:

- Oracle Database Concepts for information about the sequence generator

- Oracle Database SQL Language Reference for more information about the CURRVAL and NEXTVAL pseudocolumns

- "Editing Installation Script Files that Create Sequences"

Tutorial: Creating a Sequence

To create a sequence, use either the SQL Developer tool Create Sequence or the DDL statement CREATE SEQUENCE.

This tutorial shows how to use the Create Database Sequence tool to create a sequence to use to generate primary keys for the EVALUATIONS table (created in "Creating Tables with the CREATE TABLE Statement"). The equivalent DDL statement is:

CREATE SEQUENCE EVALUATIONS_SEQ
INCREMENT BY 1
START WITH 1 ORDER;

This sequence is part of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create EVALUATIONS_SEQ using the Create Database Sequence tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Sequences.
A list of choices appears.

3. Click New Sequence.
The Create Database Sequence window opens. The field Schema has the value HR, and the field Name has the default value, SEQUENCE1.

4. In the Name field, type EVALUATIONS_SEQ over the default value.

5. Click the tab Properties.
The Properties pane appears.

6. In the field Increment, type 1.

7. In the field Start with, type 1.

8. Deselect the check box Cycle.

9. Select the check box Order.

10. Click OK.
The sequence EVALUATIONS_SEQ is created. To see it, expand Sequences in the navigation frame.

See Also:

- Oracle Database SQL Developer User's Guide for more information about using SQL Developer to create a sequence

- Oracle Database SQL Language Reference for information about the CREATE SEQUENCE statement

- "Tutorial: Creating a Trigger that Generates a Primary Key for a Row Before It Is Inserted" to learn how to create a trigger that inserts the primary keys created by evaluations_seq into the EVALUATIONS table

Dropping Sequences

To drop a sequence, use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP SEQUENCE.

Caution:

Do not drop the sequence that you created in "Tutorial: Creating a Sequence"—you need it for later tutorials. If you want to practice dropping sequences, create new ones and then drop them.

To drop a sequence using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Sequences.
A list of sequences appears.

3. Right-click the name of the sequence to drop.
A list of choices appears.

4. Click Drop.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

Oracle Database SQL Language Reference for information about the DROP SEQUENCE statement

Creating and Managing Synonyms

A synonym is an alias for another schema object. Some reasons to use synonyms are security (for example, to hide the owner and location of an object) and convenience. Examples of convenience are:

- Using a short synonym, such as SALES, for a long object name, such as ACME_CO.SALES_DATA

- Using a synonym for a renamed object, instead of changing that object name throughout the applications that use it
For example, if your application uses a table named DEPARTMENTS, and its name changes to DIVISIONS, you can create a DEPARTMENTS synonym for that table and continue to reference it by its original name.

Topics:

- Creating Synonyms

- Dropping Synonyms

See Also:

- Oracle Database Concepts for additional general information about synonyms

Creating Synonyms

To create a synonym, use either the SQL Developer tool Create Database Synonym or the DDL statement CREATE SYNONYM.

This tutorial shows how to use the Create Database Synonym tool to create the synonym EMP for the EMPLOYEES table. The equivalent DDL statement is:

CREATE SYNONYM EMP FOR EMPLOYEES;

This synonym is part of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create a synonym using the Create Databse Synonym tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Synonyms.
A list of choices appears.

3. Click New Synonym.
The Create Database Synonym window opens. The check box Public is deselected, the field Schema has the value HR, and the field Name has the default value SYNONYM1.

4. In the Name field, type EMP over the default value.

5. Click the tab Properties.
The Properties pane appears. The Referenced Schema field has the value HR, the option Object based is deselected, and the option Name based is selected.

6. Select Object Based.
The option Name based is now deselected.

7. In the field next to the Object based option, select EMPLOYEES from the drop-down list.
Object based means that the synonym refers to a specific schema object; in this case, the table EMPLOYEES.

8. Click OK.
The synonym EMP is created. To see it, expand Synonyms in the navigation frame. You can now use EMP instead of EMPLOYEES.

See Also:

Oracle Database SQL Language Reference for information about the CREATE SYNONYM statement

Dropping Synonyms

To drop a synonym, use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP SYNONYM.

Caution:

Do not drop the synonym that you created in "Creating Synonyms"—you need it for later tutorials. If you want to practice dropping synonyms, create new ones and then drop them.

To drop a synonym using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Synonyms.
A list of synonyms appears.

3. Right-click the name of the synonym to drop.
A list of choices appears.

4. Click Drop.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

Oracle Database SQL Language Reference for information about the DROP SYNONYM statement

7 Developing Stored Subprograms and Packages

This chapter contains the following topics:

- About Stored Subprograms

- About Packages

- About PL/SQL Identifiers

- About PL/SQL Data Types

- Creating and Managing Standalone Stored Subprograms

- Creating and Managing Packages

- Declaring and Assigning Values to Variables and Constants

- Controlling Program Flow

- Using Records and Cursors

- Using Associative Arrays

- Handling Exceptions (Run-Time Errors)

Tip:

If you have problems creating or running PL/SQL code, check the Oracle Database trace files. The USER_DUMP_DEST initialization parameter specifies the current location of the trace files. You can find the value of this parameter by issuing SHOW PARAMETER USER_DUMP_DEST in the SQL Worksheet of SQL Developer or in SQL*Plus. For more information about trace files, see Oracle Database Performance Tuning Guide.

About Stored Subprograms

A subprogram is a PL/SQL unit that consists of SQL and PL/SQL statements that solve a specific problem or perform a set of related tasks. A subprogram can have parameters, whose values are supplied by the invoker. A subprogram can be either a procedure or a function. Typically, you use a procedure to perform an action and a function to compute and return a value.

A stored subprogram is a subprogram that is stored in the database. Because they are stored in the database, stored programs can be used as building blocks for many different database applications. (A subprogram that is declared within another subprogram, or within an anonymous block, is called a nested subprogram or local subprogram. It cannot be invoked from outside the subprogram or block in which it is declared. An anonymous block is a block that is not stored in the database.)

There are two kinds of stored subprograms:

- Standalone stored subprogram, which is created at schema level

- Package subprogram, which is created inside a package

Standalone stored subprograms are useful for testing pieces of program logic, but when you are sure that they work as intended, Oracle recommends that you put them into packages.

See Also:

- Oracle Database Concepts for general information about stored subprograms

- Oracle Database PL/SQL Language Reference for complete information about PL/SQL subprograms

About Packages

A package is a PL/SQL unit that consists of related subprograms and the explicit cursors and variables that they use.

Oracle recommends that you put your subprograms into packages. Some of the reasons are:

- Packages allow you to hide implementation details from client programs.
Hiding implementation details from client programs is a widely accepted best practice. Many Oracle customers follow this practice strictly, allowing client programs to access the database only by invoking PL/SQL subprograms. Some customers allow client programs to use SELECT statements to retrieve information from database tables, but require them to invoke PL/SQL subprograms for all business functions that change the database.

- Package subprograms must be qualified with package names when invoked, which ensures that their names will always work.
For example, suppose that you developed a schema-level procedure named CONTINUE before Oracle Database 11g Release 1 (11.1). Release 11.1 introduced the CONTINUE statement. Therefore, if you ported your code to 11.1, it would no longer compile. However, if you had developed your procedure inside a package, your code would refer to the procedure as package_name.CONTINUE, so the code would still compile.

- Package subprograms can send and receive records and collections.
Standalone stored subprograms can send and receive only scalar parameters—single values with no internal components, such as VARCHAR2, NUMBER, and DATE.

Note:

Oracle Database supplies many PL/SQL packages to extend database functionality and provide PL/SQL access to SQL features. You can use the supplied packages when creating your applications or for ideas in creating your own stored procedures. For information about these packages, see Oracle Database PL/SQL Packages and Types Reference.

See Also:

- Oracle Database Concepts for general information about packages

- Oracle Database PL/SQL Language Reference for more reasons to use packages

- Oracle Database PL/SQL Language Reference for complete information about PL/SQL packages

- Oracle Database PL/SQL Packages and Types Reference for complete information about the PL/SQL packages that Oracle provides

About PL/SQL Identifiers

Every PL/SQL subprogram, package, parameter, variable, constant, exception, and explicit cursor has a name, which is a PL/SQL identifier.

The minimum length of an identifier is one character; the maximum length is 30 characters. The first character must be a letter, but each later character can be either a letter, numeral, dollar sign ($), underscore (_), or number sign (#). For example, these are acceptable identifiers:

X
t2
phone#
credit_limit
LastName
oracle$number
money$$$tree
SN##
try_again_

PL/SQL is not case-sensitive for identifiers. For example, PL/SQL considers these to be the same:

lastname
LastName
LASTNAME

You cannot use a PL/SQL reserved word as an identifier. You can use a PL/SQL keyword as an identifier, but it is not recommended. For lists of PL/SQL reserved words and keywords, see Oracle Database PL/SQL Language Reference.

Tip:

Use meaningful names for identifiers, and follow a naming convention. For example, start each constant name with con_, each variable name with var_, and so on.

See Also:

- Oracle Database PL/SQL Language Reference for additional general information about PL/SQL identifiers

- Oracle Database PL/SQL Language Reference for additional information about PL/SQL naming conventions

- Oracle Database PL/SQL Language Reference for information about the scope and visibility of PL/SQL identifiers

- Oracle Database PL/SQL Language Reference for information how to collect data on PL/SQL identifiers

- Oracle Database PL/SQL Language Reference for information about how PL/SQL resolves identifier names

About PL/SQL Data Types

Every PL/SQL constant, variable, subprogram parameter, and function return value has a data type that determines its storage format, constraints, valid range of values, and operations that can be performed on it.

A PL/SQL data type is either a SQL data type (such as VARCHAR2, NUMBER, and DATE) or a PL/SQL-only data type. The latter include BOOLEAN, RECORD, REF CURSOR, and many predefined subtypes. PL/SQL also lets you define your own subtypes.

A subtype is a subset of another data type, which is called its base type. A subtype has the same valid operations as its base type, but only a subset of its valid values. Subtypes can increase reliability, provide compatibility with ANSI/ISO types, and improve readability by indicating the intended use of constants and variables.

The predefined numeric subtype PLS_INTEGER is especially useful, because its operations use hardware arithmetic, rather than the library arithmetic that its base type uses.

You cannot use PL/SQL-only data types at schema level (that is, in tables or standalone stored subprograms). Therefore, to use them in a stored subprogram, you must put the subprogram in a package.

See Also:

- Oracle Database PL/SQL Language Reference for general information about PL/SQL data types

- Oracle Database PL/SQL Language Reference for information about the PLS_INTEGER data type

- "About SQL Data Types"

Creating and Managing Standalone Stored Subprograms

Topics:

- About Subprogram Structure

- Tutorial: Creating a Standalone Stored Procedure

- Tutorial: Creating a Standalone Stored Function

- Changing Standalone Stored Subprograms

- Tutorial: Testing a Standalone Stored Function

- Dropping Standalone Stored Subprograms

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

About Subprogram Structure

A subprogram follows PL/SQL block structure; that is, it has:

- Declarative part (optional)
The declarative part contains declarations of types, constants, variables, exceptions, explicit cursors, and nested subprograms. These items are local to the subprogram and cease to exist when the subprogram completes execution.

- Executable part (required)
The executable part contains statements that assign values, control execution, and manipulate data.

- Exception-handling part (optional)
The exception-handling part contains code that handles exceptions (run-time errors).

Comments can appear anywhere in PL/SQL code. The PL/SQL compiler ignores them. Adding comments to your program promotes readability and aids understanding. A single-line comment starts with a double hyphen (--) and extends to the end of the line. A multiline comment starts with a slash and asterisk (/*) and ends with an asterisk and a slash (*/).

The structure of a procedure is:

PROCEDURE name [ ( parameter_list ) ]
{ IS | AS }
[ declarative_part ]
BEGIN  -- executable part begins
statement; [ statement; ]...
[ EXCEPTION -- executable part ends, exception-handling part begins]
exception_handler; [ exception_handler; ]... ]
END; /* exception-handling part ends if it exists;
otherwise, executable part ends */

The structure of a function is like that of a procedure, except that it includes a RETURN clause and at least one RETURN statement (and some optional clauses that are beyond the scope of this document):

FUNCTION name [ ( parameter_list ) ] RETURN data_type [ clauses ]
{ IS | AS }
[ declarative_part ]
BEGIN  -- executable part begins
-- at least one statement must be a RETURN statement
statement; [ statement; ]...
[ EXCEPTION -- executable part ends, exception-handling part begins]
exception_handler; [ exception_handler; ]... ]
END; /* exception-handling part ends if it exists;
otherwise, executable part ends */

The code that begins with PROCEDURE or FUNCTION and ends before IS or AS is the subprogram signature. The declarative, executable, and exception-handling parts comprise the subprogram body. The syntax of exception-handler is in "About Exceptions and Exception Handlers".

See Also:

Oracle Database PL/SQL Language Reference for more information about subprogram parts

Tutorial: Creating a Standalone Stored Procedure

To create a standalone stored procedure, use either the SQL Developer tool Create PL/SQL Procedure or the DDL statement CREATE PROCEDURE.

This tutorial shows how to use the Create PL/SQL Procedure tool to create a standalone stored procedure named ADD_EVALUATION that adds a row to the EVALUATIONS table (created in "Creating Tables with the CREATE TABLE Statement").

To create a standalone stored procedure using Create PL/SQL Procedure tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Procedures.
A list of choices appears.

3. Click New Procedure.
The Create PL/SQL Procedure window opens.

4. For Schema, accept the default value, HR.

5. For Name, change PROCEDURE1 to ADD_EVALUATION.

6. Click the icon Add Column.

A row appears under the column headings. Its fields have these default values: Name, param1; Type, VARCHAR2; Mode, IN; Default Value, empty.

7. For Name, change param1 to evaluation_id.

8. For Type, select NUMBER from the drop-down list.

9. For Mode, accept the default value, IN.

10. Leave Default Value empty.

11. Add a second parameter by repeating steps 6 through 10 with the Name employee_id and the Type NUMBER.

12. Add a third parameter by repeating steps 6 through 10 with the Name evaluation_date and the Type DATE.

13. Add a fourth parameter by repeating steps 6 through 10 with the Name job_id and the Type VARCHAR2.

14. Add a fifth parameter by repeating steps 6 through 10 with the Name manager_id and the Type NUMBER.

15. Add a sixth parameter by repeating steps 6 through 10 with the Name department_id and the Type NUMBER.

16. Add a seventh parameter by repeating steps 6 through 10 with the Name total_score and the Type NUMBER.

17. Click OK.
The ADD_EVALUATION pane opens, showing the CREATE PROCEDURE statement that created the procedure:

CREATE OR REPLACE
PROCEDURE ADD_EVALUATION
( evaluation_id IN NUMBER
, employee_id IN NUMBER
, evaluation_date IN DATE
, job_id IN VARCHAR2
, manager_id IN NUMBER
, department_id IN NUMBER
, total_score IN NUMBER
) AS
BEGIN
NULL;
END ADD_EVALUATION;

Because the only statement in the execution part of the procedure is NULL, the procedure does nothing.

18. Replace NULL with this statement:

INSERT INTO EVALUATIONS (
evaluation_id,
employee_id,
evaluation_date,
job_id,
manager_id,
department_id,
total_score
)
VALUES (
ADD_EVALUATION.evaluation_id,
ADD_EVALUATION.employee_id,
ADD_EVALUATION.evaluation_date,
ADD_EVALUATION.job_id,
ADD_EVALUATION.manager_id,
ADD_EVALUATION.department_id,
ADD_EVALUATION.total_score
);

(Qualifying the parameter names with the procedure name ensures that they are not confused with the columns that have the same names.)

The title of the ADD_EVALUATION pane is in italic font, indicating that the procedure is not yet saved in the database.

19. From the File menu, select Save.
Oracle Database compiles the procedure and saves it. The title of the ADD_EVALUATION pane is no longer in italic font.

See Also:

- Oracle Database SQL Developer User's Guide for another example of using SQL Developer to create a standalone stored procedure

- "About Data Definition Language (DDL) Statements" for general information that applies to the CREATE PROCEDURE statement

- Oracle Database PL/SQL Language Reference for information about the CREATE PROCEDURE statement

Tutorial: Creating a Standalone Stored Function

To create a standalone stored function, use either the SQL Developer tool Create PL/SQL Function or the DDL statement CREATE FUNCTION.

This tutorial shows how to use the Create PL/SQL Function tool to create a standalone stored function named calculate_score that has three parameters and returns a value of type NUMBER.

To create a standalone stored function using Create PL/SQL Function tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Functions.
A list of choices appears.

3. Click New Function.
The Create PL/SQL Function window opens. It looks like the Create PL/SQL Procedure window (see "Tutorial: Creating a Standalone Stored Procedure") except that its Parameters pane has a row for the value that the function returns. In that row, the value of Name is <Return> and the default value of Type is VARCHAR2.

4. For Schema, accept the default value, HR.

5. For Name, change FUNCTION1 to calculate_score.

6. In the Parameters pane, in the Type field of the only row, select NUMBER from the drop-down list.

7. Click the icon Add Column.

A row appears under the column headings. Its fields have these default values: Name, param1; Type, VARCHAR2; Mode, IN; Default Value, empty.

8. For Name, change param1 to cat.

9. For Type, accept the default, VARCHAR2.

10. For Mode, accept the default value, IN.

11. Leave Default Value empty.

12. Add a second parameter by repeating steps 7 through 11 with the Name score and the Type NUMBER.

13. Add a third parameter by repeating steps 7 through 11 with the Name weight and the Type NUMBER.

14. Click OK.
The calculate_score pane opens, showing the CREATE FUNCTION statement that created the function:

CREATE OR REPLACE
FUNCTION calculate_score
( cat IN VARCHAR2
, score IN NUMBER
, weight IN NUMBER
) RETURN NUMBER AS
BEGIN
RETURN NULL;
END calculate_score;

Because the only statement in the execution part of the function is RETURN NULL, the function does nothing.

15. Replace NULL with score * weight.
The title of the calculate_score pane is in italic font, indicating that the function is not yet saved in the database.

16. Select Save from the File menu.
Oracle Database compiles the function and saves it. The title of the calculate_score pane is no longer in italic font.

See Also:

- "About Data Definition Language (DDL) Statements" for general information that applies to the CREATE FUNCTION statement

- Oracle Database PL/SQL Language Reference for information about the CREATE FUNCTION statement

Changing Standalone Stored Subprograms

To change a standalone stored subprogram, use either the SQL Developer tool Edit or the DDL statement ALTER PROCEDURE or ALTER FUNCTION.

To change a standalone stored subprogram using the Edit tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand either Functions or Procedures.
A list of functions or procedures appears.

3. Click the function or procedure to change.
To the right of the Connections pane, a frame appears. Its top tab has the name of the subprogram to change. Under the top tab are subtabs.

4. Click the subtab Code.
The Code pane appears, showing the code that created the subprogram to change.

5. Click the icon Edit.
Another pane appears, also with the name of the subprogram to change.

6. In the pane, change the code.
The title of the pane changes to italic font, indicating that the change is not yet saved in the database.

7. Select Save from the File menu.
Oracle Database compiles the subprogram and saves it. The title of the pane is no longer in italic font.

See Also:

- "About Data Definition Language (DDL) Statements" for general information that applies to the ALTER PROCEDURE and ALTER FUNCTION statements

- Oracle Database PL/SQL Language Reference for information about the ALTER PROCEDURE statement

- Oracle Database PL/SQL Language Reference for information about the ALTER FUNCTION statement

Tutorial: Testing a Standalone Stored Function

This tutorial shows how to use the SQL Developer tool Run to test the standalone stored function calculate_score (created in "Tutorial: Creating a Standalone Stored Function").

To test the calculate_score function using the Run tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Functions.
A list of functions appears.

3. Right-click calculate_score.
A list of choices appears.

4. Click Run.
The Run PL/SQL window opens. Its PL/SQL Block frame includes this code:

v_Return := calculate_score (
CAT => CAT,
SCORE => SCORE,
WEIGHT => WEIGHT
);

5. Change the values of SCORE and WEIGHT to 8 and 0.2, respectively:

v_Return := calculate_score (
CAT => CAT,
SCORE => 8,
WEIGHT => 0.2
);

6. Click OK.
The Running - Log window opens, showing this result:

Connecting to the database hr_conn.
v_Return = 1.6
Process exited.
Disconnecting from the database hr_conn.

See Also:

Oracle Database SQL Developer User's Guide for information about using SQL Developer to run and debug procedures and functions

Dropping Standalone Stored Subprograms

To drop a standalone stored subprogram, use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP PROCEDURE or DROP FUNCTION.

To drop a standalone stored subprogram using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand either Functions or Procedures.
A list of functions or procedures appears.

3. Right-click the name of the function or procedure to drop.
A list of choices appears.

4. Click Drop.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

- "About Data Definition Language (DDL) Statements" for general information that applies to the DROP PROCEDURE and DROP FUNCTION statements

- Oracle Database SQL Language Reference for information about the DROP PROCEDURE statement

- Oracle Database SQL Language Reference for information about the DROP FUNCTION statement

Creating and Managing Packages

Topics:

- About Package Structure

- Tutorial: Creating a Package Specification

- Tutorial: Changing a Package Specification

- Tutorial: Creating a Package Body

- Dropping a Package

See Also:

"Tutorial: Declaring Variables and Constants in a Subprogram", which shows how to change a package body

About Package Structure

A package always has a specification, and it usually has a body.

The package specification defines the package, declaring the types, variables, constants, exceptions, explicit cursors, and subprograms that can be referenced from outside the package. A package specification is an application program interface (API): It has all the information that client programs need to invoke its subprograms, but no information about their implementation.

The package body defines the queries for the explicit cursors, and the code for the subprograms, that are declared in the package specification (therefore, a package with neither explicit cursors nor subprograms does not need a body). The package body can also define local subprograms, which are not declared in the specification and can be invoked only by other subprograms in the package. Package body contents are hidden from client programs. You can change the package body without invalidating the applications that call the package.

See Also:

- Oracle Database PL/SQL Language Reference for more information about the package specification

- Oracle Database PL/SQL Language Reference for more information about the package body

Tutorial: Creating a Package Specification

To create a package specification, use either the SQL Developer tool Create PL/SQL Package or the DDL statement CREATE PACKAGE.

This tutorial shows how to use the Create PL/SQL Package tool to create a specification for a package named EMP_EVAL.

This package specification is the API for the sample application that the tutorials and examples in this document show how to develop and deploy.

To create a package specification using Create PL/SQL Package tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Packages.
A list of choices appears.

3. Click New Package.
The Create PL/SQL Package window opens. The field Schema has the value HR, the field Name has the default value PACKAGE1, and the check box Add New Source In Lowercase is deselected.

4. For Schema, accept the default value, HR.

5. For Name, change PACKAGE1 to EMP_EVAL.

6. Click OK.
The EMP_EVAL pane opens, showing the CREATE PACKAGE statement that created the package:

CREATE OR REPLACE PACKAGE emp_eval AS

/* TODO enter package declarations (types, exceptions, methods etc) here */

END emp_eval;

The title of the pane is in italic font, which indicates that the package is not saved to the database.

7. (Optional) In the CREATE PACKAGE statement, replace the comment with declarations.
If you do not do this step now, you can do it later, as shown in "Tutorial: Changing a Package Specification".

8. From the File menu, select Save.
Oracle Database compiles the package and saves it. The title of the EMP_EVAL pane is no longer in italic font.

See Also:

Oracle Database PL/SQL Language Reference for information about the CREATE PACKAGE statement (for the package specification)

Tutorial: Changing a Package Specification

To change a package specification, use either the SQL Developer tool Edit or the DDL statement CREATE PACKAGE with the OR REPLACE clause.

This tutorial shows how to use the Edit tool to change the specification for the EMP_EVAL package (created in "Tutorial: Creating a Package Specification"). Specifically, the tutorial shows how to add declarations for a procedure, eval_department, and a function, calculate_score.

To change EMP_EVAL package specification using the Edit tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Right-click EMP_EVAL.
A list of choices appears.

4. Click Edit.
The EMP_EVAL pane opens, showing the CREATE PACKAGE statement that created the package:

CREATE OR REPLACE PACKAGE emp_eval AS

/* TODO enter package declarations (types, exceptions, methods etc) here */

END emp_eval;

The title of the pane is not in italic font, which indicates that the package is saved in the database.

5. In the EMP_EVAL pane, replace the comment with this code:

PROCEDURE eval_department ( dept_id IN NUMBER );

FUNCTION calculate_score ( evaluation_id IN NUMBER
, performance_id IN NUMBER)
RETURN NUMBER;

A new EMP_EVAL pane opens, showing the changed CREATE PACKAGE statement. The title of the pane is in italic font, which indicates that the changes have not been saved to the database.

6. Click the icon Compile.
The changed package specification compiles and is saved to the database. The title of the EMP_EVAL pane is no longer in italic font.

See Also:

Oracle Database PL/SQL Language Reference for information about the CREATE PACKAGE statement with the OR REPLACE clause

Tutorial: Creating a Package Body

To create a package body, use either the SQL Developer tool Create Body or the DDL statement CREATE PACKAGE BODY.

This tutorial shows how to use the Create Body tool to create a body for the EMP_EVAL package (created in "Tutorial: Creating a Package Specification" and changed in "Tutorial: Changing a Package Specification").

This package body will contain the implementation details of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create a body for the package EMP_EVAL using the Create Body tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Right-click EMP_EVAL.
A list of choices appears.

4. Click Create Body.
The EMP_EVAL Body pane appears, showing the automatically generated code for the package body:

CREATE OR REPLACE
PACKAGE BODY emp_eval AS

PROCEDURE eval_department(dept_id IN NUMBER) AS
BEGIN
/* TODO implementation required */
NULL;
END eval_department;

FUNCTION calculate_score ( evaluation_id IN NUMBER
, performance_id IN NUMBER)
RETURN NUMBER AS
BEGIN
/* TODO implementation required */
RETURN NULL;
END calculate_score;

END emp_eval;

The title of the pane is in italic font, which indicates that the code is not saved in the database.

5. (Optional) In the CREATE PACKAGE BODY statement:

- Replace the comments with executable statements.

- (Optional) In the executable part of the procedure, either delete NULL or replace it with an executable statement.

- (Optional) In the executable part of the function, either replace NULL with another expression.

If you do not do this step now, you can do it later, as shown in "Tutorial: Declaring Variables and Constants in a Subprogram".

6. Click the icon Compile.
The changed package body compiles and is saved to the database. The title of the EMP_EVAL Body pane is no longer in italic font.

See Also:

Oracle Database PL/SQL Language Reference for information about the CREATE PACKAGE BODY statement (for the package body)

Dropping a Package

To drop a package (specification and body), use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP PACKAGE.

To drop a package using the Drop tool:

1. On the Connections tab, expand the hr_conn information by clicking the plus sign (+) to the left of the hr_conn icon.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Right-click the name of the package to drop.
A list of choices appears.

4. Click Drop Package.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

Oracle Database PL/SQL Language Reference for information about the DROP PACKAGE statement

Declaring and Assigning Values to Variables and Constants

One significant advantage that PL/SQL has over SQL is that PL/SQL lets you declare and use variables and constants.

A variable or constant declared in a package specification can be used by any program that has access to the package. A variable or constant declared in a package body or subprogram is local to that package or subprogram.

A variable holds a value of a particular data type. Your program can change the value at run time. A constant holds a value that cannot be changed.

A variable or constant can have any PL/SQL data type. When declaring a variable, you can assign it an initial value; if you do not, its initial value is NULL. When declaring a constant, you must assign it an initial value. To assign an initial value to a variable or constant, use the assignment operator (:=).

Tip:

Declare all values that do not change as constants. This practice optimizes your compiled code and makes your source code easier to maintain.

Topics:

- Tutorial: Declaring Variables and Constants in a Subprogram

- Ensuring that Variables, Constants, and Parameters Have Correct Data Types

- Tutorial: Changing Declarations to Use the %TYPE Attribute

- Assigning Values to Variables

See Also:

Oracle Database PL/SQL Language Reference for general information about variables and constants

Tutorial: Declaring Variables and Constants in a Subprogram

This tutorial shows how to use the SQL Developer tool Edit to declare variables and constants in the EMP_EVAL.calculate_score function (specified in "Tutorial: Creating a Package Specification"). (This tutorial is also an example of changing a package body.)

To declare variables and constants in calculate_score function:

1. On the Connections tab, expand the hr_conn information by clicking the plus sign (+) to the left of the hr_conn icon.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Expand EMP_EVAL.
A list appears.

4. Right-click EMP_EVAL Body.
A list of choices appears.

5. Click Edit.
The EMP_EVAL Body pane appears, showing the code for the package body:

CREATE OR REPLACE
PACKAGE BODY emp_eval AS

PROCEDURE eval_department ( dept_id IN NUMBER ) AS

BEGIN
/* TODO implementation required */
NULL;
END eval_department;

FUNCTION calculate_score ( evaluation_id IN NUMBER
, performance_id IN NUMBER)
RETURN NUMBER AS
BEGIN
/* TODO implementation required */
RETURN NULL;
END calculate_score;

END emp_eval;

6. Between RETURN NUMBER AS and BEGIN, add these variable and constant declarations:

n_score       NUMBER(1,0);                -- variable
n_weight      NUMBER;                     -- variable
max_score     CONSTANT NUMBER(1,0) := 9;  -- constant, initial value 9
max_weight    CONSTANT NUMBER(8,8) := 1;  -- constant, initial value 1

7. From the File menu, select Save.
Oracle Database saves the changed package body.

See Also:

- Oracle Database PL/SQL Language Reference for general information about declaring variables and constants

- "Assigning Values to Variables with the Assignment Operator"

Ensuring that Variables, Constants, and Parameters Have Correct Data Types

After "Tutorial: Declaring Variables and Constants in a Subprogram", the code for the calculate_score function, in the body of the package EMP_EVAL, is:

FUNCTION calculate_score ( evaluation_id IN NUMBER
, performance_id IN NUMBER )
RETURN NUMBER AS
n_score       NUMBER(1,0);                -- variable
n_weight      NUMBER;                     -- variable
max_score     CONSTANT NUMBER(1,0) := 9;  -- constant, initial value 9
max_weight    CONSTANT NUMBER(8,8) := 1;  -- constant, initial value 1
BEGIN
/* TODO implementation required */
RETURN NULL;
END calculate_score;

The variables, constants, and parameters of the function represent values from the tables SCORES (created in "Creating Tables with the CREATE TABLE Statement") and PERFORMANCE_PARTS (created in "Tutorial: Creating a Table with the Create Table Tool"):

- Variable n_score will hold a value from the SCORE column of the SCORES table, and constant max_score will be compared to such values.

- Variable n_weight will hold a value from the WEIGHT column of the PERFORMANCE_PARTS table, and constant max_weight will be compared to such values.

- Parameter evaluation_id will hold a value from the EVALUATION_ID column of the SCORES table.

- Parameter performance_id will hold a value from the PERFORMANCE_ID column of the SCORES table.

Therefore, each variable, constant, and parameter has the same data type as its corresponding column.

If the data types of the columns change, you want the data types of the variables, constants, and parameters to change to the same data types; otherwise, the calculate_score function will be invalidated.

To ensure that the data types of the variables, constants, and parameters will always match those of the columns, declare them with the %TYPE attribute. The %TYPE attribute supplies the data type of a table column or another variable, ensuring the correct data type assignment.

See Also:

- Oracle Database PL/SQL Language Reference for more information about the %TYPE attribute

- Oracle Database PL/SQL Language Reference for the syntax of the %TYPE attribute

Tutorial: Changing Declarations to Use the %TYPE Attribute

This tutorial shows how to use the SQL Developer tool Edit to change the declarations of the variables, constants, and formal parameters of the EMP_EVAL.calculate_score function (shown in "Tutorial: Declaring Variables and Constants in a Subprogram") to declarations that use the %TYPE attribute.

To change the declarations in calculate_score to use %TYPE:

1. On the Connections tab, expand the hr_conn information by clicking the plus sign (+) to the left of the hr_conn icon.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Expand EMP_EVAL.
A list appears.

4. Right-click EMP_EVAL Body.
A list of choices appears.

5. Click Edit.
The EMP_EVAL Body pane appears, showing the code for the package body:

CREATE OR REPLACE
PACKAGE BODY emp_eval AS

PROCEDURE eval_department ( dept_id IN NUMBER ) AS
BEGIN
/* TODO implementation required */
NULL;
END eval_department;

FUNCTION calculate_score ( evaluation_id IN NUMBER
, performance_id IN NUMBER )
RETURN NUMBER AS
n_score       NUMBER(1,0);                -- variable
n_weight      NUMBER;                     -- variable
max_score     CONSTANT NUMBER(1,0) := 9;  -- constant, initial value 9
max_weight    CONSTANT NUMBER(8,8) := 1;  -- constant, initial value 1
BEGIN
/* TODO implementation required */
RETURN NULL;
END calculate_score;

END emp_eval;

6. In the code for the function, make the changes shown in bold font:

FUNCTION calculate_score ( evaluation_id IN SCORES.EVALUATION_ID%TYPE
, performance_id IN SCORES.PERFORMANCE_ID%TYPE)
RETURN NUMBER AS
n_score       SCORES.SCORE%TYPE;
n_weight      PERFORMANCE_PARTS.WEIGHT%TYPE;
max_score     CONSTANT SCORES.SCORE%TYPE := 9;
max_weight    CONSTANT PERFORMANCE_PARTS.WEIGHT%TYPE := 1;

7. Right-click EMP_EVAL.
A list of choices appears.

8. Click Edit.
The EMP_EVAL pane opens, showing the CREATE PACKAGE statement that created the package:

CREATE OR REPLACE PACKAGE emp_eval AS

PROCEDURE eval_department(dept_id IN NUMBER);
FUNCTION calculate_score(evaluation_id IN NUMBER
, performance_id IN NUMBER)
RETURN NUMBER;

END emp_eval;

9. In the code for the function, make the changes shown in bold font:

FUNCTION calculate_score(evaluation_id IN scores.evaluation_id%TYPE
, performance_id IN scores.performance_id%TYPE)

10. Right-click EMP_EVAL.
A list of choices appears.

11. Click Compile.

Assigning Values to Variables

You can assign a value to a variable in these ways:

- Use the assignment operator to assign it the value of an expression.

- Use the SELECT INTO or FETCH statement to assign it a value from a table.

- Pass it to a subprogram as an OUT or IN OUT parameter, and then assign the value inside the subprogram

- Bind the variable to a value.

Topics:

- Assigning Values to Variables with the Assignment Operator

- Assigning Values to Variables with the SELECT INTO Statement

See Also:

- Oracle Database PL/SQL Language Reference for more information about assigning values to variables

- Oracle Database 2 Day + .NET Developer's Guide for information about binding variables

- Oracle Database 2 Day + PHP Developer's Guide for information about binding variables

- Oracle Database 2 Day + Java Developer's Guide for information about binding variables

- Oracle Database 2 Day + Application Express Developer's Guide for information about binding variables

Assigning Values to Variables with the Assignment Operator

With the assignment operator (:=), you can assign the value of an expression to a variable in either the declarative or executable part of a subprogram.

In the declarative part of a subprogram, you can assign an initial value to a variable when you declare it. The syntax is:

variable_name data_type := expression;

In the executable part of a subprogram, you can assign a value to a variable with an assignment statement. The syntax is:

variable_name := expression;

Example 7-1 shows, in bold font, the changes to make to the EMP_EVAL.calculate_score function to add a variable, running_total, and use it as the return value of the function. The assignment operator appears in both the declarative and executable parts of the function. (The data type of running_total must be NUMBER, rather than SCORES.SCORE%TYPE or PERFORMANCE_PARTS.WEIGHT%TYPE, because it holds the product of two NUMBER values with different precisions and scales.)

Example 7-1 Assigning Values to a Variable with Assignment Operator

FUNCTION calculate_score(evaluation_id IN SCORES.EVALUATION_ID%TYPE
, performance_id IN SCORES.PERFORMANCE_ID%TYPE)
RETURN NUMBER AS
n_score       SCORES.SCORE%TYPE;
n_weight      PERFORMANCE_PARTS.WEIGHT%TYPE;
running_total NUMBER := 0;
max_score     CONSTANT SCORES.SCORE%TYPE := 9;
max_weight    CONSTANT PERFORMANCE_PARTS.WEIGHT%TYPE:= 1;
BEGIN
running_total := max_score * max_weight;
RETURN running_total;
END calculate_score;

See Also:

- Oracle Database PL/SQL Language Reference for variable declaration syntax

- Oracle Database PL/SQL Language Reference for assignment statement syntax

Assigning Values to Variables with the SELECT INTO Statement

To use table values in subprograms or packages, you must assign them to variables with SELECT INTO statements.

Example 7-2 shows, in bold font, the changes to make to the EMP_EVAL.calculate_score function to have it calculate running_total from table values.

Example 7-2 Assigning Table Values to Variables with SELECT INTO

FUNCTION calculate_score ( evaluation_id IN scores.evaluation_id%TYPE
, performance_id IN scores.performance_id%TYPE )
RETURN NUMBER AS

n_score       scores.score%TYPE;
n_weight      performance_parts.weight%TYPE;
running_total NUMBER := 0;
max_score     CONSTANT scores.score%TYPE := 9;
max_weight    CONSTANT performance_parts.weight%TYPE:= 1;
BEGIN
SELECT s.score INTO n_score
FROM SCORES s
WHERE evaluation_id = s.evaluation_id
AND performance_id = s.performance_id;

SELECT p.weight INTO n_weight
FROM PERFORMANCE_PARTS p
WHERE performance_id = p.performance_id;

running_total := n_score * n_weight;
RETURN running_total;
END calculate_score;

The add_eval procedure in Example 7-3 inserts a row into the EVALUATIONS table, using values from the corresponding row in the EMPLOYEES table. Add the add_eval procedure to the body of the EMP_EVAL package, but not to the specification. Because it is not in the specification, add_eval is local to the package—it can be invoked only by other subprograms in the package, not from outside the package.

Example 7-3 Inserting a Table Row with Values from Another Table

PROCEDURE add_eval ( employee_id IN EMPLOYEES.EMPLOYEE_ID%TYPE
, today IN DATE )
AS
job_id         EMPLOYEES.JOB_ID%TYPE;
manager_id     EMPLOYEES.MANAGER_ID%TYPE;
department_id  EMPLOYEES.DEPARTMENT_ID%TYPE;
BEGIN
SELECT e.job_id INTO job_id
FROM EMPLOYEES e
WHERE employee_id = e.employee_id;

SELECT e.manager_id INTO manager_id
FROM EMPLOYEES e
WHERE employee_id = e.employee_id;

SELECT e.department_id INTO department_id
FROM EMPLOYEES e
WHERE employee_id = e.employee_id;

INSERT INTO EVALUATIONS (
evaluation_id,
employee_id,
evaluation_date,
job_id,
manager_id,
department_id,
total_score
)
VALUES (
evaluations_seq.NEXTVAL,   -- evaluation_id
add_eval.employee_id,      -- employee_id
add_eval.today,            -- evaluation_date
add_eval.job_id,           -- job_id
add_eval.manager_id,       -- manager_id
add_eval.department_id,    -- department_id
0                          -- total_score
);
END add_eval;

See Also:

Oracle Database PL/SQL Language Reference for more information about the SELECT INTO statement

Controlling Program Flow

Unlike SQL, which runs statements in the order in which you enter them, PL/SQL has control statements that let you control the flow of your program.

Topics:

- About Control Statements

- Using the IF Statement

- Using the CASE Statement

- Using the FOR LOOP Statement

- Using the WHILE LOOP Statement

- Using the Basic LOOP and EXIT WHEN Statements

About Control Statements

PL/SQL has three categories of control statements:

- Conditional selection statements, which let you execute different statements for different data values.
The conditional selection statements are IF and and CASE.

- Loop statements, which let you repeat the same statements with a series of different data values.
The loop statements are FOR LOOP, WHILE LOOP and basic LOOP.

The EXIT statement transfers control to the end of a loop. The CONTINUE statement exits the current iteration of a loop and transfers control to the next iteration. Both EXIT and CONTINUE have an optional WHEN clause, in which you can specify a condition.

- Sequential control statements, which let you go to a specified, labeled statement, or to do nothing.
The sequential control statements are GOTO and and NULL.

See Also:

- Oracle Database PL/SQL Language Reference for an overview of PL/SQL control statements

Using the IF Statement

The IF statement either executes or skips a sequence of statements, depending on the value of a Boolean expression.

The IF statement has this syntax:

IF boolean_expression THEN statement [, statement ]
[ ELSEIF boolean_expression THEN statement [, statement ] ]...
[ ELSE  statement [, statement ] ]
END IF;

Suppose that your company evaluates employees twice a year in the first 10 years of employment, but only once a year afterward. You want a function that returns the evaluation frequency for an employee. You can use an IF statement to determine the return value of the function, as in Example 7-4.

Add the eval_frequency function to the body of the EMP_EVAL package, but not to the specification. Because it is not in the specification, eval_frequency is local to the package—it can be invoked only by other subprograms in the package, not from outside the package.

Example 7-4 IF Statement that Determines Return Value of Function

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date     EMPLOYEES.HIRE_DATE%TYPE;
today      EMPLOYEES.HIRE_DATE%TYPE;
eval_freq  PLS_INTEGER;
BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;
ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

See Also:

- Oracle Database PL/SQL Language Reference for the syntax of the IF statement

- Oracle Database PL/SQL Language Reference for more information about using the IF statement

Using the CASE Statement

The CASE statement chooses from a sequence of conditions, and executes the corresponding statement.

The simple CASE statement evaluates a single expression and compares it to several potential values. It has this syntax:

CASE expression
WHEN value THEN statement
[ WHEN value THEN statement ]...
[ ELSE statement [, statement ]... ]
END CASE;

The searched CASE statement evaluates multiple Boolean expressions and chooses the first one whose value is TRUE. For information about the searched CASE statement, see Oracle Database PL/SQL Language Reference.

Tip:

When you can use either a CASE statement or nested IF statements, use a CASE statement—it is both more readable and more efficient.

Suppose that, if an employee is evaluated only once a year, you want the eval_frequency function to suggest a salary increase, which depends on the JOB_ID.

Add the CASE statement shown in Example 7-5 to the eval_frequency function. (For information about the procedure that prints the strings, DBMS_OUTPUT.PUT_LINE, see Oracle Database PL/SQL Packages and Types Reference.)

Example 7-5 CASE Statement that Determines Which String to Print

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date     EMPLOYEES.HIRE_DATE%TYPE;
today      EMPLOYEES.HIRE_DATE%TYPE;
eval_freq  PLS_INTEGER;
j_id       EMPLOYEES.JOB_ID%TYPE;

BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;

SELECT JOB_ID INTO j_id
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

CASE j_id
WHEN 'PU_CLERK' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 8% salary increase for employee # ' || emp_id);
WHEN 'SH_CLERK' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 7% salary increase for employee # ' || emp_id);
WHEN 'ST_CLERK' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 6% salary increase for employee # ' || emp_id);
WHEN 'HR_REP' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 5% salary increase for employee # ' || emp_id);
WHEN 'PR_REP' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 5% salary increase for employee # ' || emp_id);
WHEN 'MK_REP' THEN DBMS_OUTPUT.PUT_LINE(
'Consider 4% salary increase for employee # ' || emp_id);
ELSE DBMS_OUTPUT.PUT_LINE(
'Nothing to do for employee #' || emp_id);
END CASE;
ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

See Also:

- "Using CASE Expressions in Queries"

- Oracle Database PL/SQL Language Reference for the syntax of the CASE statement

- Oracle Database PL/SQL Language Reference for more information about using the CASE statement

Using the FOR LOOP Statement

The FOR LOOP statement repeats a sequence of statements once for each integer in the range lower_bound through upper_bound. Its syntax is:

FOR counter IN lower_bound..upper_bound LOOP
statement [, statement ]...
END LOOP;

The statements between LOOP and END LOOP can use counter, but cannot change its value.

Suppose that, instead of only suggesting a salary increase, you want the eval_frequency function to report what the salary would be if it increased by the suggested amount every year for five years.

Change the eval_frequency function as shown in bold font in Example 7-6. (For information about the procedures that prints the strings, DBMS_OUTPUT.PUT_LINE, see Oracle Database PL/SQL Packages and Types Reference.)

Example 7-6 FOR LOOP Statement that Computes Salary After Five Years

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date      EMPLOYEES.HIRE_DATE%TYPE;
today       EMPLOYEES.HIRE_DATE%TYPE;
eval_freq   PLS_INTEGER;
j_id        EMPLOYEES.JOB_ID%TYPE;
sal         EMPLOYEES.SALARY%TYPE;
sal_raise   NUMBER(3,3) := 0;

BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;

SELECT JOB_ID INTO j_id
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT SALARY INTO sal
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

CASE j_id
WHEN 'PU_CLERK' THEN sal_raise := 0.08;
WHEN 'SH_CLERK' THEN sal_raise := 0.07;
WHEN 'ST_CLERK' THEN sal_raise := 0.06;
WHEN 'HR_REP'   THEN sal_raise := 0.05;
WHEN 'PR_REP'   THEN sal_raise := 0.05;
WHEN 'MK_REP'   THEN sal_raise := 0.04;
ELSE NULL;
END CASE;

IF (sal_raise != 0) THEN
BEGIN
DBMS_OUTPUT.PUT_LINE('If salary ' || sal || ' increases by ' ||
ROUND((sal_raise * 100),0) ||
'% each year for 5 years, it will be:');

FOR i IN 1..5 LOOP
sal := sal * (1 + sal_raise);
DBMS_OUTPUT.PUT_LINE(ROUND(sal, 2) || ' after ' || i || ' year(s)');
END LOOP;
END;
END IF;

ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

See Also:

- Oracle Database PL/SQL Language Reference for the syntax of the FOR LOOP statement

- Oracle Database PL/SQL Language Reference for more information about using the FOR LOOP statement

Using the WHILE LOOP Statement

The WHILE LOOP statement repeats a sequence of statements while a condition is TRUE. Its syntax is:

WHILE condition LOOP
statement [, statement ]...
END LOOP;

Note:

If the statements between LOOP and END LOOP never cause condition to become FALSE, the WHILE LOOP statement runs indefinitely.

Suppose that the eval_frequency function uses the WHILE LOOP statement instead of the FOR LOOP statement, and ends after the proposed salary exceeds the maximum salary for the JOB_ID.

Change the eval_frequency function as shown in bold font in Example 7-7. (For information about the procedures that prints the strings, DBMS_OUTPUT.PUT_LINE, see Oracle Database PL/SQL Packages and Types Reference.)

Example 7-7 WHILE LOOP Statement that Computes Salary to Maximum

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date      EMPLOYEES.HIRE_DATE%TYPE;
today       EMPLOYEES.HIRE_DATE%TYPE;
eval_freq   PLS_INTEGER;
j_id        EMPLOYEES.JOB_ID%TYPE;
sal         EMPLOYEES.SALARY%TYPE;
sal_raise   NUMBER(3,3) := 0;
sal_max     JOBS.MAX_SALARY%TYPE;

BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;

SELECT JOB_ID INTO j_id
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT SALARY INTO sal
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT MAX_SALARY INTO sal_max
FROM JOBS
WHERE JOB_ID = j_id;

CASE j_id
WHEN 'PU_CLERK' THEN sal_raise := 0.08;
WHEN 'SH_CLERK' THEN sal_raise := 0.07;
WHEN 'ST_CLERK' THEN sal_raise := 0.06;
WHEN 'HR_REP'   THEN sal_raise := 0.05;
WHEN 'PR_REP'   THEN sal_raise := 0.05;
WHEN 'MK_REP'   THEN sal_raise := 0.04;
ELSE NULL;
END CASE;

IF (sal_raise != 0) THEN
BEGIN
DBMS_OUTPUT.PUT_LINE('If salary ' || sal || ' increases by ' ||
ROUND((sal_raise * 100),0) ||
'% each year, it will be:');

WHILE sal <= sal_max LOOP
sal := sal * (1 + sal_raise);
DBMS_OUTPUT.PUT_LINE(ROUND(sal, 2));
END LOOP;

DBMS_OUTPUT.PUT_LINE('Maximum salary for this job is ' || sal_max);
END;
END IF;
ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

See Also:

- Oracle Database PL/SQL Language Reference for the syntax of the WHILE LOOP statement

- Oracle Database PL/SQL Language Reference for more information about using the WHILE LOOP statement

Using the Basic LOOP and EXIT WHEN Statements

The basic LOOP statement repeats a sequence of statements. Its syntax is:

LOOP
statement [, statement ]...
END LOOP;

At least one statement must be an EXIT statement; otherwise, the LOOP statement runs indefinitely.

The EXIT WHEN statement (the EXIT statement with its optional WHEN clause) exits a loop when a condition is TRUE and transfers control to the end of the loop.

In the eval_frequency function, in the last iteration of the WHILE LOOP statement, the last computed value usually exceeds the maximum salary.

Change the WHILE LOOP statement to a basic LOOP statement that includes an EXIT WHEN statement, as shown in Example 7-8.
WHILE LOOP

Example 7-8 Using the EXIT WHEN Statement

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date      EMPLOYEES.HIRE_DATE%TYPE;
today       EMPLOYEES.HIRE_DATE%TYPE;
eval_freq   PLS_INTEGER;
j_id        EMPLOYEES.JOB_ID%TYPE;
sal         EMPLOYEES.SALARY%TYPE;
sal_raise   NUMBER(3,3) := 0;
sal_max     JOBS.MAX_SALARY%TYPE;

BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;

SELECT JOB_ID INTO j_id
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT SALARY INTO sal
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT MAX_SALARY INTO sal_max
FROM JOBS
WHERE JOB_ID = j_id;

CASE j_id
WHEN 'PU_CLERK' THEN sal_raise := 0.08;
WHEN 'SH_CLERK' THEN sal_raise := 0.07;
WHEN 'ST_CLERK' THEN sal_raise := 0.06;
WHEN 'HR_REP'   THEN sal_raise := 0.05;
WHEN 'PR_REP'   THEN sal_raise := 0.05;
WHEN 'MK_REP'   THEN sal_raise := 0.04;
ELSE NULL;
END CASE;

IF (sal_raise != 0) THEN
BEGIN
DBMS_OUTPUT.PUT_LINE('If salary ' || sal || ' increases by ' ||
ROUND((sal_raise * 100),0) ||
'% each year, it will be:');

LOOP
sal := sal * (1 + sal_raise);
EXIT WHEN sal > sal_max;
DBMS_OUTPUT.PUT_LINE(ROUND(sal,2));
END LOOP;

DBMS_OUTPUT.PUT_LINE('Maximum salary for this job is ' || sal_max);
END;
END IF;
ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

See Also:

- Oracle Database PL/SQL Language Reference for the syntax of the LOOP statement

- Oracle Database PL/SQL Language Reference for the syntax of the EXIT statement

- Oracle Database PL/SQL Language Reference for more information about using the LOOP and EXIT statements

Using Records and Cursors

Topics:

- About Records

- Tutorial: Declaring a RECORD Type

- Tutorial: Creating and Invoking a Subprogram with a Record Parameter

- About Cursors

- Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

- Tutorial: Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

- About Cursor Variables

- Using a Cursor Variable to Retrieve Result Set Rows One at a Time

- Tutorial: Using a Cursor Variable to Retrieve Result Set Rows One at a Time

See Also:

Oracle Database PL/SQL Language Reference for more information about records

About Records

A record is a PL/SQL composite variable that can store data values of different types, similar to a struct type in C, C++, or Java. The internal components of a record are called fields. To access a record field, you use dot notation: record_name.field_name.

You can treat record fields like scalar variables. You can also pass entire records as subprogram parameters (if neither the sending nor receiving subprogram is a standalone stored subprogram).

Records are useful for holding data from table rows, or from certain columns of table rows. Each record field corresponds to a table column.

There are three ways to create a record:

- Declare a RECORD type, and then declare a variable of that type.
The syntax is:

TYPE record_name IS RECORD
( field_name data_type [:= initial_value]
[, field_name data_type [:= initial_value ] ]... );

variable_name record_name;

- Declare a variable of the type table_name%ROWTYPE.
The fields of the record have the same names and data types as the columns of the table.

- Declare a variable of the type cursor_name%ROWTYPE.
The fields of the record have the same names and data types as the columns of the table in the FROM clause of the cursor SELECT statement.

See Also:

- Oracle Database PL/SQL Language Reference for more information about defining RECORD types and declaring records of that type

- Oracle Database PL/SQL Language Reference for the syntax of a RECORD type definition

- Oracle Database PL/SQL Language Reference for more information about the %ROWTYPE attribute

- Oracle Database PL/SQL Language Reference for the syntax of the %ROWTYPE attribute

Tutorial: Declaring a RECORD Type

This tutorial shows how to use the SQL Developer tool Edit to declare a RECORD type, sal_info, whose fields can hold salary information for an employee—job ID, minimum and maximum salary for that job ID, current salary, and suggested raise.

To declare RECORD type sal_info:

1. On the Connections tab, expand the hr_conn information by clicking the plus sign (+) to the left of the hr_conn icon.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Right-click EMP_EVAL.
A list of choices appears.

4. Click Edit.
The EMP_EVAL pane opens, showing the CREATE PACKAGE statement that created the package:

CREATE OR REPLACE PACKAGE emp_eval AS

PROCEDURE eval_department(dept_id IN NUMBER);
FUNCTION calculate_score(evaluation_id IN NUMBER
, performance_id IN NUMBER)
RETURN NUMBER;

END emp_eval;

5. In the EMP_EVAL pane, immediately before END emp_eval, add this code:

TYPE sal_info IS RECORD
( j_id     jobs.job_id%type
, sal_min  jobs.min_salary%type
, sal_max  jobs.max_salary%type
, sal      employees.salary%type
, sal_raise NUMBER(3,3) );

A new EMP_EVAL pane opens, showing the changed CREATE PACKAGE statement. The title of the pane is in italic font, which indicates that the changes have not been saved to the database.

6. Click the icon Compile.
The changed package specification compiles and is saved to the database. The title of the EMP_EVAL pane is no longer in italic font.

Now you can declare records of the type sal_info, as in "Tutorial: Creating and Invoking a Subprogram with a Record Parameter".

Tutorial: Creating and Invoking a Subprogram with a Record Parameter

If you declared the RECORD type sal_info in "Tutorial: Declaring a RECORD Type", this tutorial shows how to use the SQL Developer tool Edit to do the following:

- Create a procedure, salary_schedule, which has a parameter of type sal_info.

- Change the eval_frequency function so that it declares a record, emp_sal, of the type sal_info, populates its fields, and passes it to the salary_schedule procedure.

Because eval_frequency will invoke salary_schedule, the declaration of salary_schedule must precede the declaration of eval_frequency (otherwise, the package will not compile). However, the definition of salary_schedule can be anywhere in the package body.

To create salary_schedule and change eval_frequency:

1. On the Connections tab, expand the hr_conn information by clicking the plus sign (+) to the left of the hr_conn icon.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Packages.
A list of packages appears.

3. Expand EMP_EVAL.
A list appears.

4. Right-click EMP_EVAL Body.
A list of choices appears.

5. Click Edit.
The EMP_EVAL Body pane appears, showing the code for the package body.

6. In the EMP_EVAL Body pane, immediately before END emp_eval, add this definition of the salary_schedule procedure:

PROCEDURE salary_schedule (emp IN sal_info) AS
accumulating_sal  NUMBER;
BEGIN
DBMS_OUTPUT.PUT_LINE('If salary ' || emp.sal ||
' increases by ' || ROUND((emp.sal_raise * 100),0) ||
'% each year, it will be:');

accumulating_sal := emp.sal;

WHILE accumulating_sal <= emp.sal_max LOOP
accumulating_sal := accumulating_sal * (1 + emp.sal_raise);
DBMS_OUTPUT.PUT_LINE(ROUND(accumulating_sal,2) ||', ');
END LOOP;
END salary_schedule;

A new EMP_EVAL Body pane opens, showing the changed CREATE PACKAGE BODY statement. The title of the pane is in italic font, which indicates that the changes have not been saved to the database.

7. In the EMP_EVAL Body pane, enter the code shown in bold font, in this position:

create or replace
PACKAGE BODY EMP_EVAL AS

FUNCTION eval_frequency (emp_id EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER;
PROCEDURE salary_schedule(emp IN sal_info);
PROCEDURE add_eval(employee_id IN employees.employee_id%type, today IN DATE);

PROCEDURE eval_department (dept_id IN NUMBER) AS

8. Edit the eval_frequency function, making the changes shown in bold font:

FUNCTION eval_frequency (emp_id EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER
AS
h_date     EMPLOYEES.HIRE_DATE%TYPE;
today      EMPLOYEES.HIRE_DATE%TYPE;
eval_freq  PLS_INTEGER;
emp_sal    SAL_INFO;  -- replaces sal, sal_raise, and sal_max

BEGIN
SELECT SYSDATE INTO today FROM DUAL;

SELECT HIRE_DATE INTO h_date
FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

IF ((h_date + (INTERVAL '120' MONTH)) < today) THEN
eval_freq := 1;

/* populate emp_sal */

SELECT JOB_ID INTO emp_sal.j_id FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

SELECT MIN_SALARY INTO emp_sal.sal_min FROM JOBS
WHERE JOB_ID = emp_sal.j_id;

SELECT MAX_SALARY INTO emp_sal.sal_max FROM JOBS
WHERE JOB_ID = emp_sal.j_id;

SELECT SALARY INTO emp_sal.sal FROM EMPLOYEES
WHERE EMPLOYEE_ID = emp_id;

emp_sal.sal_raise := 0;  -- default

CASE emp_sal.j_id
WHEN 'PU_CLERK' THEN emp_sal.sal_raise := 0.08;
WHEN 'SH_CLERK' THEN emp_sal.sal_raise := 0.07;
WHEN 'ST_CLERK' THEN emp_sal.sal_raise := 0.06;
WHEN 'HR_REP' THEN emp_sal.sal_raise := 0.05;
WHEN 'PR_REP' THEN emp_sal.sal_raise := 0.05;
WHEN 'MK_REP' THEN emp_sal.sal_raise := 0.04;
ELSE NULL;
END CASE;

IF (emp_sal.sal_raise != 0) THEN
salary_schedule(emp_sal);
END IF;
ELSE
eval_freq := 2;
END IF;

RETURN eval_freq;
END eval_frequency;

9. Click Compile.

About Cursors

When Oracle Database executes a SQL statement, it stores the result set and processing information in an unnamed private SQL area. A pointer to this unnamed area, called a cursor, lets you retrieve the rows of the result set one at a time. Cursor attributes return information about the state of the cursor.

Every time you run either a SQL DML statement or a PL/SQL SELECT INTO statement, PL/SQL opens an implicit cursor. You can get information about this cursor from its attributes, but you cannot control it. After the statement runs, the database closes the cursor; however, its attribute values remain available until another DML or SELECT INTO statement runs.

PL/SQL also lets you declare explicit cursors. An explicit cursor has a name and is associated with a query (SQL SELECT statement)—usually one that returns multiple rows. After declaring an explicit cursor, you must open it (with the OPEN statement), fetch rows one at a time from the result set (with the FETCH statement), and close the cursor (with the CLOSE statement). After closing the cursor, you can neither fetch records from the result set nor see the cursor attribute values.

The syntax for the value of an implicit cursor attribute is SQLattribute (for example, SQL%FOUND). SQLattribute always refers to the most recently run DML or SELECT INTO statement.

The syntax for the value of an explicit cursor attribute is cursor_name immediately followed by attribute (for example, c1%FOUND).

Table 7-1 lists the cursor attributes and the values that they can return. (Implicit cursors have additional attributes that are beyond the scope of this book.)

Table 7-1 Cursor Attribute Values

Attribute

Values for Explicit Cursor

Values for Implicit Cursor

%FOUND

If cursor is not open, INVALID_CURSOR.

If cursor is open but no fetch was attempted, NULL.

If the most recent fetch returned a row, TRUE.

If the most recent fetch did not return a row, FALSE.

If no DML or SELECT INTO statement has run, NULL.

If the most recent DML or SELECT INTO statement returned a row, TRUE.

If the most recent DML or SELECT INTO statement did not return a row, FALSE.

%NOTFOUND

If cursor is not open, INVALID_CURSOR.

If cursor is open but no fetch was attempted, NULL.

If the most recent fetch returned a row, FALSE.

If the most recent fetch did not return a row, TRUE.

If no DML or SELECT INTO statement has run, NULL.

If the most recent DML or SELECT INTO statement returned a row, FALSE.

If the most recent DML or SELECT INTO statement did not return a row, TRUE.

%ROWCOUNT

If cursor is not open, INVALID_CURSOR; otherwise, a number greater than or equal to zero.

NULL if no DML or SELECT INTO statement has run; otherwise, a number greater than or equal to zero.

%ISOPEN

If cursor is open, TRUE; if not, FALSE.

Always FALSE.

See Also:

- "About Queries"

- "About Data Manipulation Language (DML) Statements"

- Oracle Database PL/SQL Language Reference for more information about the SELECT INTO statement

- Oracle Database Advanced Application Developer's Guide for more information about using cursors in applications

- Oracle Database PL/SQL Language Reference for more information about managing cursors in PL/SQL

Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

The following procedure uses each necessary statement in its simplest form, but provides references to its complete syntax.

To use an explicit cursor to retrieve result set rows one at a time:

1. In the declarative part:

1. Declare the cursor:

CURSOR cursor_name IS query;

For complete explicit cursor declaration syntax, see Oracle Database PL/SQL Language Reference.

2. Declare a record to hold the row returned by the cursor:

record_name cursor_name%ROWTYPE;

For complete %ROWTYPE syntax, see Oracle Database PL/SQL Language Reference.

2. In the executable part:

1. Open the cursor:

OPEN cursor_name;

For complete OPEN statement syntax, see Oracle Database PL/SQL Language Reference.

2. Fetch rows from the cursor (rows from the result set) one at a time, using a LOOP statement that has syntax similar to this:

LOOP
FETCH cursor_name INTO record_name;
EXIT WHEN cursor_name%NOTFOUND;
-- Process row that is in record_name:
statement;
[ statement; ]...
END LOOP;

For complete FETCH statement syntax, see Oracle Database PL/SQL Language Reference.

3. Close the cursor:

CLOSE cursor_name;

For complete CLOSE statement syntax, see Oracle Database PL/SQL Language Reference.

Tutorial: Using an Explicit Cursor to Retrieve Result Set Rows One at a Time

This tutorial shows how to implement the procedure EMP_EVAL.eval_department, which uses an explicit cursor, emp_cursor.

To implement the EMP_EVAL.eval_department procedure:

1. In the EMP_EVAL package specification, change the declaration of the eval_department procedure as shown in bold font:

PROCEDURE eval_department(dept_id IN employees.department_id%TYPE);

(For instructions for changing a package specification, see "Tutorial: Changing a Package Specification".)

2. In the EMP_EVAL package body, change the definition of the eval_department procedure as shown in bold font:

PROCEDURE eval_department (dept_id IN employees.department_id%TYPE)
AS
CURSOR emp_cursor IS
SELECT * FROM EMPLOYEES
WHERE DEPARTMENT_ID = dept_id;

emp_record  EMPLOYEES%ROWTYPE;  -- for row returned by cursor
all_evals   BOOLEAN;  -- true if all employees in dept need evaluations
today       DATE;

BEGIN
today := SYSDATE;

IF (EXTRACT(MONTH FROM today) < 6) THEN
all_evals := FALSE; -- only new employees need evaluations
ELSE
all_evals := TRUE;  -- all employees need evaluations
END IF;

OPEN emp_cursor;

DBMS_OUTPUT.PUT_LINE (
'Determining evaluations necessary in department # ' ||
dept_id );

LOOP
FETCH emp_cursor INTO emp_record;
EXIT WHEN emp_cursor%NOTFOUND;

IF all_evals THEN
add_eval(emp_record.employee_id, today);
ELSIF (eval_frequency(emp_record.employee_id) = 2) THEN
add_eval(emp_record.employee_id, today);
END IF;
END LOOP;

DBMS_OUTPUT.PUT_LINE('Processed ' || emp_cursor%ROWCOUNT || ' records.');

CLOSE emp_cursor;
END eval_department;

(For a step-by-step example of changing a package body, see "Tutorial: Declaring Variables and Constants in a Subprogram".)

3. Compile the EMP_EVAL package specification.

4. Compile the EMP_EVAL package body.

About Cursor Variables

A cursor variable is like a cursor (see "About Cursors"), except that it is not limited to one query. You can open a cursor variable for a query, process the result set, and then use the cursor variable for another query. Cursor variables are useful for passing query results between subprograms.

To declare a cursor variable, you declare a REF CURSOR type, and then declare a variable of that type (therefore, a cursor variable is often called a REF CURSOR). A REF CURSOR type can be either strong or weak.

A strong REF CURSOR type specifies a return type, which is the RECORD type of its cursor variables. The PL/SQL compiler does not allow you to use these strongly typed cursor variables for queries that return rows that are not of the return type. Strong REF CURSOR types are less error-prone than weak ones, but weak ones are more flexible.

A weak REF CURSOR type does not specify a return type. The PL/SQL compiler accepts weakly typed cursor variables in any queries. Weak REF CURSOR types are interchangeable; therefore, instead of creating weak REF CURSOR types, you can use the predefined type weak cursor type SYS_REFCURSOR.

After declaring a cursor variable, you must open it for a specific query (with the OPEN FOR statement), fetch rows one at a time from the result set (with the FETCH statement), and then either close the cursor (with the CLOSE statement) or open it for another specific query (with the OPEN FOR statement). Opening the cursor variable for another query closes it for the previous query. After closing a cursor variable for a specific query, you can neither fetch records from the result set of that query nor see the cursor attribute values for that query.

See Also:

- Oracle Database PL/SQL Language Reference for more information about using cursor variables

- Oracle Database PL/SQL Language Reference for the syntax of cursor variable declaration

Using a Cursor Variable to Retrieve Result Set Rows One at a Time

The following procedure uses each of the necessary statements in its simplest form, but provides references to their complete syntax.

To use a cursor variable to retrieve result set rows one at a time:

1. In the declarative part:

1. Declare the REF CURSOR type:

TYPE cursor_type IS REF CURSOR [ RETURN return_type ];

For complete REF CURSOR type declaration syntax, see Oracle Database PL/SQL Language Reference.

2. Declare a cursor variable of that type:

cursor_variable cursor_type;

For complete cursor variable declaration syntax, see Oracle Database PL/SQL Language Reference.

3. Declare a record to hold the row returned by the cursor:

record_name return_type;

For complete information about record declaration syntax, see Oracle Database PL/SQL Language Reference.

2. In the executable part:

1. Open the cursor variable for a specific query:

OPEN cursor_variable FOR query;

For complete information about OPEN FOR statement syntax, see Oracle Database PL/SQL Language Reference.

2. Fetch rows from the cursor variable (rows from the result set) one at a time, using a LOOP statement that has syntax similar to this:

LOOP
FETCH cursor_variable INTO record_name;
EXIT WHEN cursor_variable%NOTFOUND;
-- Process row that is in record_name:
statement;
[ statement; ]...
END LOOP;

For complete information about FETCH statement syntax, see Oracle Database PL/SQL Language Reference.

3. Close the cursor variable:

CLOSE cursor_variable;

Alternatively, you can open the cursor variable for another query, which closes it for the current query.

For complete information about CLOSE statement syntax, see Oracle Database PL/SQL Language Reference.

Tutorial: Using a Cursor Variable to Retrieve Result Set Rows One at a Time

This tutorial shows how to change the EMP_EVAL.eval_department procedure so that it uses a cursor variable instead of an explicit cursor, which lets it process multiple departments. The change includes adding a procedure that uses the cursor variable.

This tutorial also shows how to make EMP_EVAL.eval_department and EMP_EVAL.add_eval more efficient: Instead of passing one field of a record to add_eval and having add_eval use three queries to extract three other fields of the same record, eval_department passes the entire record to add_eval, and add_eval uses dot notation to access the values of the other three fields.

To change the EMP_EVAL.eval_department procedure to use a cursor variable:

1. In the EMP_EVAL package specification, add the procedure declaration and the REF CURSOR type definition, as shown in bold font:

create or replace
PACKAGE emp_eval AS

PROCEDURE eval_department (dept_id IN employees.department_id%TYPE);

PROCEDURE eval_everyone;

FUNCTION calculate_score(eval_id IN scores.evaluation_id%TYPE
, perf_id IN scores.performance_id%TYPE)
RETURN NUMBER;
TYPE SAL_INFO IS RECORD
( j_id jobs.job_id%type
, sal_min jobs.min_salary%type
, sal_max jobs.max_salary%type
, salary employees.salary%type
, sal_raise NUMBER(3,3));

TYPE emp_refcursor_type IS REF CURSOR RETURN employees%ROWTYPE;
END emp_eval;

(For instructions for changing a package specification, see "Tutorial: Changing a Package Specification".)

2. In the EMP_EVAL package body, add a forward declaration for the procedure eval_loop_control and change the declaration of the procedure add_eval, as shown in bold font:

create or replace
PACKAGE BODY EMP_EVAL AS

FUNCTION eval_frequency (emp_id IN EMPLOYEES.EMPLOYEE_ID%TYPE)
RETURN PLS_INTEGER;

PROCEDURE salary_schedule(emp IN sal_info);

PROCEDURE add_eval(emp_record IN EMPLOYEES%ROWTYPE, today IN DATE);

PROCEDURE eval_loop_control(emp_cursor IN emp_refcursor_type);
...

(For a step-by-step example of changing a package body, see "Tutorial: Declaring Variables and Constants in a Subprogram".)

3. Change the eval_department procedure to retrieve three separate result sets based on the department, and to invoke the eval_loop_control procedure, as shown in bold font:

PROCEDURE eval_department(dept_id IN employees.department_id%TYPE) AS
emp_cursor    emp_refcursor_type;
current_dept  departments.department_id%TYPE;

BEGIN
current_dept := dept_id;

FOR loop_c IN 1..3 LOOP
OPEN emp_cursor FOR
SELECT *
FROM employees
WHERE current_dept = dept_id;

DBMS_OUTPUT.PUT_LINE
('Determining necessary evaluations in department #' ||
current_dept);

eval_loop_control(emp_cursor);

DBMS_OUTPUT.PUT_LINE
('Processed ' || emp_cursor%ROWCOUNT || ' records.');

CLOSE emp_cursor;
current_dept := current_dept + 10;
END LOOP;
END eval_department;

4. Change the add_eval as shown in bold font:

PROCEDURE add_eval(emp_record IN employees%ROWTYPE, today IN DATE)
AS
-- (Delete local variables)
BEGIN
INSERT INTO EVALUATIONS (
evaluation_id,
employee_id,
evaluation_date,
job_id,
manager_id,
department_id,
total_score
)
VALUES (
evaluations_seq.NEXTVAL,   -- evaluation_id
emp_record.employee_id,    -- employee_id
today,                     -- evaluation_date
emp_record.job_id,         -- job_id
emp_record.manager_id,     -- manager_id
emp_record.department_id,  -- department_id
0                           -- total_score
);
END add_eval;

5. Before END EMP_EVAL, add the following procedure, which fetches the individual records from the result set and processes them:

PROCEDURE eval_loop_control (emp_cursor IN emp_refcursor_type) AS
emp_record      EMPLOYEES%ROWTYPE;
all_evals       BOOLEAN;
today           DATE;
BEGIN
today := SYSDATE;

IF (EXTRACT(MONTH FROM today) < 6) THEN
all_evals := FALSE;
ELSE
all_evals := TRUE;
END IF;

LOOP
FETCH emp_cursor INTO emp_record;
EXIT WHEN emp_cursor%NOTFOUND;

IF all_evals THEN
add_eval(emp_record, today);
ELSIF (eval_frequency(emp_record.employee_id) = 2) THEN
add_eval(emp_record, today);
END IF;
END LOOP;
END eval_loop_control;

6. Before END EMP_EVAL, add the following procedure, which retrieves a result set that contains all employees in the company:

PROCEDURE eval_everyone AS
emp_cursor emp_refcursor_type;
BEGIN
OPEN emp_cursor FOR SELECT * FROM employees;
DBMS_OUTPUT.PUT_LINE('Determining number of necessary evaluations.');
eval_loop_control(emp_cursor);
DBMS_OUTPUT.PUT_LINE('Processed ' || emp_cursor%ROWCOUNT || ' records.');
CLOSE emp_cursor;
END eval_everyone;

7. Compile the EMP_EVAL package specification.

8. Compile the EMP_EVAL package body.

Using Associative Arrays

An associative array is a type of collection.

Topics:

- About Collections

- About Associative Arrays

- Declaring Associative Arrays

- Populating Associative Arrays

- Traversing Dense Associative Arrays

- Traversing Sparse Associative Arrays

See Also:

For more information about collections:

- Oracle Database Concepts

- Oracle Database PL/SQL Language Reference

About Collections

A collection is a PL/SQL composite variable that stores elements of the same type in a specified order, similar to a one-dimensional array. The internal components of a collection are called elements. Each element has a unique subscript that identifies its position in the collection. To access a collection element, you use subscript notation: collection_name(element_subscript).

You can treat collection elements like scalar variables. You can also pass entire collections as subprogram parameters (if neither the sending nor receiving subprogram is a standalone stored subprogram).

A collection method is a built-in PL/SQL subprogram that either returns information about a collection or operates on a collection. To invoke a collection method, you use dot notation: collection_name.method_name. For example, collection_name.COUNT returns the number of elements in the collection.

PL/SQL has three types of collections:

- Associative arrays (formerly called "PL/SQL tables" or "index-by tables")

- Nested tables

- Variable arrays (varrays)

This document explains only associative arrays.

See Also:

- Oracle Database PL/SQL Language Reference for more information about PL/SQL collection types

- Oracle Database PL/SQL Language Reference for more information about collection methods

About Associative Arrays

An associative array is an unbounded set of key-value pairs. Each key is unique, and serves as the subscript of the element that holds the corresponding value. Therefore, you can access elements without knowing their positions in the array, and without traversing the array.

The data type of the key can be either PLS_INTEGER or VARCHAR2 (length).

If the data type of the key is PLS_INTEGER, and the associative array is indexed by integer, and it is dense (that is, it has no gaps between elements), then every element between the first and last element is defined and has a value (which can be NULL).

If the key type is VARCHAR2 (length), the associative array is indexed by string (of length characters), and it is sparse; that is, it might have gaps between elements.

When traversing a dense associative array, you do not need to beware of gaps between elements; when traversing a sparse associative array, you do.

To assign a value to an associative array element, you can use an assignment operator:

array_name(key) := value

If key is not in the array, the assignment statement adds the key-value pair to the array. Otherwise, the statement changes the value of array_name(key) to value.

Associative arrays are useful for storing data temporarily. They do not use the disk space or network operations that tables require. However, because associative arrays are intended for temporary storage, you cannot manipulate them with DML statements or use SELECT INTO statements to assign their values to variables.

If you declare an associative array in a package, and assign values to the variable in the package body, then the associative array exists for the life of the database session. Otherwise, it exists for the life of the subprogram in which you declare it.

See Also:

Oracle Database PL/SQL Language Reference for more information about associative arrays

Declaring Associative Arrays

To declare an associative array, you declare an associative array type, and then declare a variable of that type. The simplest syntax is:

TYPE array_type IS TABLE OF element_type INDEX BY key_type;

array_name  array_type;

An efficient way to declare an associative array is with a cursor, using the following procedure. The procedure uses each necessary statement in its simplest form, but provides references to its complete syntax.

To use a cursor to declare an associative array:

1. In the declarative part:

1. Declare the cursor:

CURSOR cursor_name IS query;

For complete explicit cursor declaration syntax, see Oracle Database PL/SQL Language Reference.

2. Declare the associative array type:

TYPE array_type IS TABLE OF cursor_name%ROWTYPE
INDEX BY { PLS_INTEGER | VARCHAR2 length }

For complete associative array type declaration syntax, see Oracle Database PL/SQL Language Reference.

3. Declare an associative array variable of that type:

array_name  array_type;

For complete variable declaration syntax, see Oracle Database PL/SQL Language Reference.

Example 7-9 uses the preceding procedure to declare two associative arrays, employees_jobs and jobs_, and then declares a third associative array, job_titles_type, without using a cursor. The first two arrays are indexed by integer; the third is indexed by string.

Note:

The ORDER BY clause in the declaration of employees_jobs_cursor determines the storage order of the elements of the associative array employee_jobs.

Example 7-9 Declaring Associative Arrays

DECLARE
-- Declare cursor:

CURSOR employees_jobs_cursor IS
SELECT FIRST_NAME, LAST_NAME, JOB_ID
FROM EMPLOYEES
ORDER BY JOB_ID, LAST_NAME, FIRST_NAME;

-- Declare associative array type:

TYPE employees_jobs_type IS TABLE OF employees_jobs_cursor%ROWTYPE
INDEX BY PLS_INTEGER;

-- Declare associative array:

employees_jobs  employees_jobs_type;

-- Use same procedure to declare another associative array:

CURSOR jobs_cursor IS
SELECT JOB_ID, JOB_TITLE
FROM JOBS;

TYPE jobs_type IS TABLE OF jobs_cursor%ROWTYPE
INDEX BY PLS_INTEGER;

jobs_  jobs_type;

-- Declare associative array without using cursor:

TYPE job_titles_type IS TABLE OF JOBS.JOB_TITLE%TYPE
INDEX BY JOBS.JOB_ID%TYPE;  -- jobs.job_id%type is varchar2(10)

job_titles  job_titles_type;

BEGIN
NULL;
END;
/

See Also:

- "About Cursors"

- Oracle Database PL/SQL Language Reference for associative array declaration syntax

Populating Associative Arrays

The most efficient way to populate a dense associative array is with a cursor and the FETCH statement with the BULK COLLECT INTO clause, using the following procedure. The procedure uses each necessary statement in its simplest form, but provides references to its complete syntax.

You cannot use the following procedure to populate a sparse associative array. Instead, you must use an assignment statement inside a loop statement. For information about loop statements, see "Controlling Program Flow".

To use a cursor to populate an associative array indexed by integer:

1. If you have not done so, declare an associative array with a cursor, using the procedure in "Declaring Associative Arrays".

2. In the executable part of the PL/SQL unit in which you declared the associative array:

1. Open the cursor:

OPEN cursor_name;

For complete OPEN statement syntax, see Oracle Database PL/SQL Language Reference.

2. Fetch all rows from the cursor into the associative array variable at once, using a FETCH statement with the BULK COLLECT INTO clause:

FETCH cursor_name BULK COLLECT INTO aa_variable;

For complete FETCH statement syntax, see Oracle Database PL/SQL Language Reference.

3. Close the cursor:

CLOSE cursor_name;

For complete CLOSE statement syntax, see Oracle Database PL/SQL Language Reference.

Example 7-10 uses the preceding procedure to populate the associative arrays employees_jobs and jobs_, which are indexed by integer. Then it uses an assignment statement inside a FOR LOOP statement to populate the associative array job_titles_type, which is indexed by string.
FOR LOOP

Example 7-10 Populating Associative Arrays

-- Declarative part from Example 7-9 goes here.
BEGIN
-- Populate associative arrays indexed by integer:

OPEN employees_jobs_cursor;
FETCH employees_jobs_cursor BULK COLLECT INTO employees_jobs;
CLOSE employees_jobs_cursor;

OPEN jobs_cursor;
FETCH jobs_cursor BULK COLLECT INTO jobs_;
CLOSE jobs_cursor;

-- Populate associative array indexed by string:

FOR i IN 1..jobs_.COUNT() LOOP
job_titles(jobs_(i).job_id) := jobs_(i).job_title;
END LOOP;
END;
/

See Also:

"About Cursors"

Traversing Dense Associative Arrays

A dense associative array (indexed by integer) has no gaps between elements—every element between the first and last element is defined and has a value (which can be NULL). You can traverse a dense array with a FOR LOOP statement, as in Example 7-11.

When inserted in the executable part of Example 7-10, after the code that populates the employees_jobs array, the FOR LOOP statement in Example 7-11 prints the elements of the employees_jobs array in the order in which they were stored. Their storage order was determined by the ORDER BY clause in the declaration of employees_jobs_cursor, which was used to declare employees_jobs (see Example 7-9).
FOR LOOPFOR LOOP
The upper bound of the FOR LOOP statement, employees_jobs. COUNT, invokes a collection method that returns the number of elements in the array. For more information about COUNT, see Oracle Database PL/SQL Language Reference.

Example 7-11 Traversing a Dense Associative Array

-- Code that populates employees_jobs must precede this code:

FOR i IN 1..employees_jobs.COUNT LOOP
DBMS_OUTPUT.PUT_LINE(
RPAD(employees_jobs(i).first_name, 23) ||
RPAD(employees_jobs(i).last_name,  28) ||     employees_jobs(i).job_id);
END LOOP;

Result:

William                Gietz                       AC_ACCOUNT
Shelley                Higgins                     AC_MGR
Jennifer               Whalen                      AD_ASST
Steven                 King                        AD_PRES
Lex                    De Haan                     AD_VP
Neena                  Kochhar                     AD_VP
John                   Chen                        FI_ACCOUNT
...
Jose Manuel            Urman                       FI_ACCOUNT
Nancy                  Greenberg                   FI_MGR
Susan                  Mavris                      HR_REP
David                  Austin                      IT_PROG
...
Valli                  Pataballa                   IT_PROG
Michael                Hartstein                   MK_MAN
Pat                    Fay                         MK_REP
Hermann                Baer                        PR_REP
Shelli                 Baida                       PU_CLERK
...
Sigal                  Tobias                      PU_CLERK
Den                    Raphaely                    PU_MAN
Gerald                 Cambrault                   SA_MAN
...
Eleni                  Zlotkey                     SA_MAN
Ellen                  Abel                        SA_REP
...
Clara                  Vishney                     SA_REP
Sarah                  Bell                        SH_CLERK
...
Peter                  Vargas                      ST_CLERK
Adam                   Fripp                       ST_MAN
...
Matthew                Weiss                       ST_MAN

Traversing Sparse Associative Arrays

A sparse associative array (indexed by string) might have gaps between elements. You can traverse it with a WHILE LOOP statement, as in Example 7-12.

To run the code in Example 7-12, which prints the elements of the job_titles array:

1. At the end of the declarative part of Example 7-9, insert this variable declaration:

i jobs_.job_id%TYPE;

2. In the executable part of Example 7-10, after the code that populates the job_titles array, insert the code from Example 7-12.

Example 7-12 includes two collection method invocations, job_titles.FIRST and job_titles.NEXT(i). job_titles.FIRST returns the first element of job_titles, and job_titles.NEXT(i) returns the subscript that succeeds i. For more information about FIRST, see Oracle Database PL/SQL Language Reference. For more information about NEXT, see Oracle Database PL/SQL Language Reference.
WHILE LOOP

Example 7-12 Traversing a Sparse Associative Array

/* Declare this variable in declarative part:

i jobs_.job_id%TYPE;

Add this code to the executable part,
after code that populates job_titles:
*/

i := job_titles.FIRST;

WHILE i IS NOT NULL LOOP
DBMS_OUTPUT.PUT_LINE(RPAD(i, 12) || job_titles(i));
i := job_titles.NEXT(i);
END LOOP;

Result:

AC_ACCOUNT  Public Accountant
AC_MGR      Accounting Manager
AD_ASST     Administration Assistant
AD_PRES     President
AD_VP       Administration Vice President
FI_ACCOUNT  Accountant
FI_MGR      Finance Manager
HR_REP      Human Resources Representative
IT_PROG     Programmer
MK_MAN      Marketing Manager
MK_REP      Marketing Representative
PR_REP      Public Relations Representative
PU_CLERK    Purchasing Clerk
PU_MAN      Purchasing Manager
SA_MAN      Sales Manager
SA_REP      Sales Representative
SH_CLERK    Shipping Clerk
ST_CLERK    Stock Clerk
ST_MAN      Stock Manager

Handling Exceptions (Run-Time Errors)

Topics:

- About Exceptions and Exception Handlers

- Handling Predefined Exceptions

- Declaring and Handling User-Defined Exceptions

See Also:

Oracle Database PL/SQL Language Reference for more information about handling PL/SQL errors

About Exceptions and Exception Handlers

When a run-time error occurs in PL/SQL code, an exception is raised. If the subprogram (or block) in which the exception is raised has an exception-handling part, control transfers to it; otherwise, execution stops.

Run-time errors can arise from design faults, coding mistakes, hardware failures, and many other sources. Because you cannot anticipate all possible errors, Oracle recommends including exception-handling parts in your subprograms ("About Subprogram Structure" shows where to put the exception-handling part).

Oracle Database has many predefined exceptions, which it raises automatically when a program violates database rules or exceeds system-dependent limits. For example, if a SELECT INTO statement returns no rows, Oracle Database raises the predefined exception NO_DATA_FOUND. For a summary of predefined PL/SQL exceptions, see Oracle Database PL/SQL Language Reference.

PL/SQL lets you define (declare) your own exceptions. An exception declaration has this syntax:

exception_name EXCEPTION;

Unlike a predefined exception, a user-defined exception must be raised explicitly, using either the RAISE statement or the DBMS_STANDARD.RAISE_APPLICATION_ERROR procedure. For example:

IF condition THEN RAISE exception_name;

For information about the DBMS_STANDARD.RAISE_APPLICATION_ERROR procedure, see Oracle Database PL/SQL Language Reference.

The exception-handling part of a subprogram contains one or more exception handlers. An exception handler has this syntax:

WHEN { exception_name [ OR exception_name ]... | OTHERS } THEN
statement; [ statement; ]...

A WHEN OTHERS exception handler handles unexpected run-time errors. If used, it must be last. For example:

EXCEPTION
WHEN exception_1 THEN
statement; [ statement; ]...
WHEN exception_2 OR exception_3 THEN
statement; [ statement; ]...
WHEN OTHERS THEN
statement; [ statement; ]...
END;

An alternative to the WHEN OTHERS exception handler is the EXCEPTION_INIT pragma, which associates a user-defined exception name with an Oracle Database error number.

See Also:

- Oracle Database PL/SQL Language Reference for more information about exception declaration syntax

- Oracle Database PL/SQL Language Reference for more information about exception handler syntax

- Oracle Database PL/SQL Language Reference for more information about the EXCEPTION_INIT pragma

Handling Predefined Exceptions

Example 7-13 shows, in bold font, how to change the EMP_EVAL.eval_department procedure to handle the predefined exception NO_DATA_FOUND. Make this change and compile the changed procedure. (For an example of how to change a package body, see "Tutorial: Declaring Variables and Constants in a Subprogram".)

Example 7-13 Handling Predefined Exception NO_DATA_FOUND

PROCEDURE eval_department(dept_id IN employees.department_id%TYPE) AS
emp_cursor    emp_refcursor_type;
current_dept  departments.department_id%TYPE;

BEGIN
current_dept := dept_id;

FOR loop_c IN 1..3 LOOP
OPEN emp_cursor FOR
SELECT *
FROM employees
WHERE current_dept = dept_id;

DBMS_OUTPUT.PUT_LINE
('Determining necessary evaluations in department #' ||
current_dept);

eval_loop_control(emp_cursor);

DBMS_OUTPUT.PUT_LINE
('Processed ' || emp_cursor%ROWCOUNT || ' records.');

CLOSE emp_cursor;
current_dept := current_dept + 10;
END LOOP;
EXCEPTION
WHEN NO_DATA_FOUND THEN
DBMS_OUTPUT.PUT_LINE ('The query did not return a result set');
END eval_department;

See Also:

- Oracle Database PL/SQL Language Reference for more information about predefined exceptions

- Oracle Database PL/SQL Language Reference for more information about handling raised exceptions

Declaring and Handling User-Defined Exceptions

Example 7-14 shows, in bold font, how to change the EMP_EVAL.calculate_score function to declare and handle two user-defined exceptions, wrong_weight and wrong_score. Make this change and compile the changed function. (For an example of how to change a package body, see "Tutorial: Declaring Variables and Constants in a Subprogram".)

Example 7-14 Handling User-Defined Exceptions

FUNCTION calculate_score ( evaluation_id IN scores.evaluation_id%TYPE
, performance_id IN scores.performance_id%TYPE )
RETURN NUMBER AS

weight_wrong  EXCEPTION;
score_wrong   EXCEPTION;
n_score       scores.score%TYPE;
n_weight      performance_parts.weight%TYPE;
running_total NUMBER := 0;
max_score     CONSTANT scores.score%TYPE := 9;
max_weight    CONSTANT performance_parts.weight%TYPE:= 1;
BEGIN
SELECT s.score INTO n_score
FROM SCORES s
WHERE evaluation_id = s.evaluation_id
AND performance_id = s.performance_id;

SELECT p.weight INTO n_weight
FROM PERFORMANCE_PARTS p
WHERE performance_id = p.performance_id;

BEGIN
IF (n_weight > max_weight) OR (n_weight < 0) THEN
RAISE weight_wrong;
END IF;
END;

BEGIN
IF (n_score > max_score) OR (n_score < 0) THEN
RAISE score_wrong;
END IF;
END;

running_total := n_score * n_weight;
RETURN running_total;

EXCEPTION
WHEN weight_wrong THEN
DBMS_OUTPUT.PUT_LINE(
'The weight of a score must be between 0 and ' || max_weight);
RETURN -1;
WHEN score_wrong THEN
DBMS_OUTPUT.PUT_LINE(
'The score must be between 0 and ' || max_score);
RETURN -1;
END calculate_score;

See Also:

- Oracle Database PL/SQL Language Reference for more information about user-defined exceptions

- Oracle Database PL/SQL Language Reference for more information about handling raised exceptions

8 Using Triggers

This chapter contains the following topics:

- About Triggers

- Creating Triggers

- Changing Triggers

- Disabling and Enabling Triggers

- About Trigger Compilation and Dependencies

- Dropping Triggers

About Triggers

A trigger is a PL/SQL unit that is stored in the database and (if it is in the enabled state) automatically executes ("fires") in response to a specified event.

A trigger has this structure:

TRIGGER trigger_name
triggering_event
[ trigger_restriction ]
BEGIN
triggered_action;
END;

The trigger_name must be unique for triggers in the schema. A trigger can have the same name as another kind of object in the schema (for example, a table); however, Oracle recommends using a naming convention that avoids confusion.

If the trigger is in the enabled state, the triggering_event causes the database to execute the triggered_action if the trigger_restriction is either TRUE or omitted. The triggering_event is associated with either a table, a view, a schema, or the database, and it is one of these:

- DML statement (described in "About Data Manipulation Language (DML) Statements")

- DDL statement (described in "About Data Definition Language (DDL) Statements")

- Database operation (SERVERERROR, LOGON, LOGOFF, STARTUP, or SHUTDOWN)

If the trigger is in the disabled state, the triggering_event does not cause the database to execute the triggered_action, even if the trigger_restriction is TRUE or omitted.

By default, a trigger is created in the enabled state. You can disable an enabled trigger, and enable a disabled trigger.

Unlike a subprogram, a trigger cannot be invoked directly. A trigger is invoked only by its triggering event, which can be caused by any user or application. You might be unaware that a trigger is executing unless it causes an error that is not handled properly.

A simple trigger can fire at exactly one of these timing points:

- Before the triggering event executes (statement-level BEFORE trigger)

- After the triggering event executes (statement-level AFTER trigger)

- Before each row that the event affects (row-level BEFORE trigger)

- After each row that the event affects (row-level AFTER trigger)

A compound trigger can fire at multiple timing points. For information about compound triggers, see Oracle Database PL/SQL Language Reference.

An INSTEAD OF trigger is defined on a view, and its triggering event is a DML statement. Instead of executing the DML statement, Oracle Database executes the INSTEAD OF trigger. For more information, see "Creating an INSTEAD OF Trigger".

A system trigger is defined on a schema or the database. A trigger defined on a schema fires for each event associated with the owner of the schema (the current user). A trigger defined on a database fires for each event associated with all users.

One use of triggers is to enforce business rules that apply to all client applications. For example, suppose that data added to the EMPLOYEES table must have a certain format, and that many client applications can add data to this table. A trigger on the table can ensure the proper format of all data added to it. Because the trigger executes whenever any client adds data to the table, no client can circumvent the rules, and the code that enforces the rules can be stored and maintained only in the trigger, rather than in every client application. For other uses of triggers, see Oracle Database PL/SQL Language Reference.

See Also:

Oracle Database PL/SQL Language Reference for complete information about triggers

Creating Triggers

To create triggers, use either the SQL Developer tool Create Trigger or the DDL statement CREATE TRIGGER. This topic shows how to use both of these ways to create triggers.

By default, a trigger is created in the enabled state. To create a trigger in disabled state, use the CREATE TRIGGER statement with the DISABLE clause.

Note:

To create triggers, you must have appropriate privileges; however, for this discussion and simple application, you do not need this additional information.

Topics:

- About OLD and NEW Pseudorecords

- Tutorial: Creating a Trigger that Logs Table Changes

- Tutorial: Creating a Trigger that Generates a Primary Key for a Row Before It Is Inserted

- Creating an INSTEAD OF Trigger

- Creating Triggers that Log LOGON and LOGOFF Events

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

See Also:

- Oracle Database SQL Developer User's Guide for information about SQL Developer dialog boxes for creating objects

- Oracle Database PL/SQL Language Reference for more information about the CREATE TRIGGER statement

- "Editing Installation Script Files that Create Triggers"

About OLD and NEW Pseudorecords

When a row-level trigger fires, the PL/SQL run-time system creates and populates the two pseudorecords OLD and NEW. They are called pseudorecords because they have some, but not all, of the properties of records.

For the row that the trigger is processing:

- For an INSERT trigger, OLD contains no values, and NEW contains the new values.

- For an UPDATE trigger, OLD contains the old values, and NEW contains the new values.

- For a DELETE trigger, OLD contains the old values, and NEW contains no values.

To reference a pseudorecord, put a colon before its name—:OLD or :NEW—as in Example 8-1.

See Also:

Oracle Database PL/SQL Language Reference for more information about OLD and NEW pseudorecords

Tutorial: Creating a Trigger that Logs Table Changes

This tutorial shows how to use the CREATE TRIGGER statement to create a trigger, EVAL_CHANGE_TRIGGER, which adds a row to the table EVALUATIONS_LOG whenever an INSERT, UPDATE, or DELETE statement changes the EVALUATIONS table.

The trigger adds the row after the triggering statement executes, and uses the conditional predicates INSERTING, UPDATING, and DELETING to determine which of the three possible DML statements fired the trigger.

EVAL_CHANGE_TRIGGER is a statement-level trigger and an AFTER trigger.

This trigger is part of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create EVALUATIONS_LOG and EVAL_CHANGE_TRIGGER:

1. Create the EVALUATIONS_LOG table:

CREATE TABLE EVALUATIONS_LOG ( log_date DATE
, action VARCHAR2(50));

2. Create EVAL_CHANGE_TRIGGER:

CREATE OR REPLACE TRIGGER EVAL_CHANGE_TRIGGER
AFTER INSERT OR UPDATE OR DELETE
ON EVALUATIONS
DECLARE
log_action  EVALUATIONS_LOG.action%TYPE;
BEGIN
IF INSERTING THEN
log_action := 'Insert';
ELSIF UPDATING THEN
log_action := 'Update';
ELSIF DELETING THEN
log_action := 'Delete';
ELSE
DBMS_OUTPUT.PUT_LINE('This code is not reachable.');
END IF;

INSERT INTO EVALUATIONS_LOG (log_date, action)
VALUES (SYSDATE, log_action);
END;

Tutorial: Creating a Trigger that Generates a Primary Key for a Row Before It Is Inserted

The sequence EVALUATIONS_SEQ, created in "Creating and Managing Sequences", generates primary keys for the EVALUATIONS table. However, these primary keys are not inserted into the table automatically.

This tutorial shows how to use the SQL Developer Create Trigger tool to create a trigger named NEW_EVALUATION_TRIGGER, which fires before a row is inserted into the EVALUATIONS table, and generates the unique number for the primary key of that row, using evaluations_seq. The trigger fires once for each row affected by the triggering INSERT statement.

NEW_EVALUATION_TRIGGER is a row-level trigger and a BEFORE trigger.

This trigger is part of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create the NEW_EVALUATION trigger:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Right-click Triggers.
A list of choices appears.

3. Click New Trigger.
The Create Trigger window opens. The field Schema has the value HR and the field Name has the default value TRIGGER1.

4. In the Name field, type NEW_EVALUATION_TRIGGER over the default value.

5. Click the tab Trigger.
The Trigger pane appears. By default, the field Trigger Type has the value TABLE, the check box Enabled is selected, the field Table Owner has the value HR, the field Table Name has the value COUNTRIES, the options Before and Statement Level are selected, the options After and Row Level are deselected, and the check boxes Insert, Update, and Delete are deselected.

6. In the field Table Name, from the drop-down menu, select EVALUATIONS.

7. Select the option Row Level.
The option Statement Level is now deselected.

8. Select the check box Insert.

9. Click OK.
The NEW_EVALUATION_TRIGGER pane opens, showing the CREATE TRIGGER statement that created the trigger:

CREATE OR REPLACE
TRIGGER NEW_EVALUATION_TRIGGER
BEFORE INSERT ON EVALUATIONS
FOR EACH ROW
BEGIN
NULL;
END;

10. In the CREATE TRIGGER statement, replace NULL with this:

:NEW.evaluation_id := evaluations_seq.NEXTVAL

The title of the NEW_EVALUATION_TRIGGER pane is in italic font, indicating that the trigger is not yet saved in the database.

11. From the File menu, select Save.
Oracle Database compiles the procedure and saves it. The title of the NEW_EVALUATION_TRIGGER pane is no longer in italic font.

Creating an INSTEAD OF Trigger

A view presents the output of a query as a table. If you want to change a view as you would change a table, you must create INSTEAD OF triggers. Instead of changing the view, they change the underlying tables.

For example, consider the view EMP_LOCATIONS, whose NAME column is created from the LAST_NAME and FIRST_NAME columns of the EMPLOYEES table:

CREATE VIEW EMP_LOCATIONS AS
SELECT e.EMPLOYEE_ID,
e.LAST_NAME || ', ' || e.FIRST_NAME NAME,
d.DEPARTMENT_NAME DEPARTMENT,
l.CITY CITY,
c.COUNTRY_NAME COUNTRY
FROM EMPLOYEES e, DEPARTMENTS d, LOCATIONS l, COUNTRIES c
WHERE e.DEPARTMENT_ID = d.DEPARTMENT_ID AND
d.LOCATION_ID = l.LOCATION_ID AND
l.COUNTRY_ID = c.COUNTRY_ID
ORDER BY LAST_NAME;

To update EMP_LOCATIONS.NAME, you must update EMPLOYEES.LAST_NAME and EMPLOYEES.FIRST_NAME. This is what the INSTEAD OF trigger in Example 8-1 does.

This trigger is part of the sample application that the tutorials and examples in this document show how to develop and deploy.

NEW and OLD are pseudorecords that the PL/SQL run-time engine creates and populates whenever a row-level trigger fires. OLD and NEW store the original and new values, respectively, of the record being processed by the trigger. They are called pseudorecords because they do not have all properties of PL/SQL records.

Example 8-1 Creating an INSTEAD OF Trigger

CREATE OR REPLACE TRIGGER update_name_view_trigger
INSTEAD OF UPDATE ON emp_locations
BEGIN
UPDATE employees SET
first_name = substr( :NEW.name, instr( :new.name, ',' )+2),
last_name = substr( :NEW.name, 1, instr( :new.name, ',')-1)
WHERE employee_id = :OLD.employee_id;
END;

See Also:

Oracle Database PL/SQL Language Reference

Creating Triggers that Log LOGON and LOGOFF Events

This tutorial shows how to use the CREATE TRIGGER statement to create two triggers, hr_logon_trigger and hr_logoff_trigger. After someone logs on as user HR, hr_logon_trigger adds a row to the table HR_USERS_LOG. Before someone logs off as user HR, hr_logoff_trigger adds a row to the table HR_USERS_LOG.

hr_logon_trigger and hr_logoff_trigger are system triggers. hr_logon_trigger is a BEFORE trigger, and hr_logoff_trigger is an AFTER trigger.

These triggers are not part of the sample application that the tutorials and examples in this document show how to develop and deploy.

To create HR_USERS_LOG, HR_LOGON_TRIGGER, and HR_LOGOFF_TRIGGER:

1. Create the HR_USERS_LOG table:

CREATE TABLE hr_users_log (
user_name VARCHAR2(30),
activity VARCHAR2(20),
event_date DATE
);

2. Create hr_logon_trigger:

CREATE OR REPLACE TRIGGER hr_logon_trigger
AFTER LOGON
ON HR.SCHEMA
BEGIN
INSERT INTO hr_users_log (user_name, activity, event_date)
VALUES (USER, 'LOGON', SYSDATE);
END;

3. Create hr_logoff_trigger:

CREATE OR REPLACE TRIGGER hr_logoff_trigger
BEFORE LOGOFF
ON HR.SCHEMA
BEGIN
INSERT INTO hr_users_log (user_name, activity, event_date)
VALUES (USER, 'LOGOFF', SYSDATE);
END;

Changing Triggers

To change a trigger, use either the SQL Developer tool Edit or the DDL statement CREATE TRIGGER with the OR REPLACE clause.

To change a standalone stored subprogram using the Edit tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Triggers.
A list of triggers appears.

3. Click the trigger to change.
To the right of the Connections pane, a frame with appears. Its top tab has the name of the trigger to change. Under the top tab are subtabs.

4. Click the subtab Code.
The Code pane appears. It shows the code that created the trigger to change.

5. On the Code pane, click the icon Edit.
Another pane appears, also with the name of the trigger to change.

6. In the pane, change the code.
The title of the pane is in italic font, indicating that the change is not yet saved in the database.

7. Select Save from the File menu.
Oracle Database compiles the trigger and saves it. The title of the pane is no longer in italic font.

See Also:

- "About Data Definition Language (DDL) Statements" for general information that applies to the CREATE OR REPLACE TRIGGER statement

- Oracle Database PL/SQL Language Reference for more information about the CREATE OR REPLACE TRIGGER statement

Disabling and Enabling Triggers

You might need to temporarily disable triggers if they reference objects that are unavailable, or if you must upload a large amount of data without the delay that triggers cause (as in a recovery operation). After the referenced objects become available, or you have finished uploading the data, you can re-enable the triggers.

To disable or enable a single trigger, use the ALTER TRIGGER statement with the DISABLE or ENABLE clause. For example:

ALTER TRIGGER eval_change_trigger DISABLE;
ALTER TRIGGER eval_change_trigger ENABLE;

To disable or enable all triggers on a particular table, use the ALTER TABLE statement with the DISABLE ALL TRIGGERS or ENABLE ALL TRIGGERS clause. For example:

ALTER TABLE evaluations DISABLE ALL TRIGGERS;
ALTER TABLE evaluations ENABLE ALL TRIGGERS;

See Also:

- Oracle Database PL/SQL Language Reference for more information about the ALTER TRIGGER statement

- Oracle Database SQL Language Reference for more information about the ALTER TABLE statement

About Trigger Compilation and Dependencies

Running a CREATE TRIGGER statement compiles the trigger being created. If this compilation causes an error, the CREATE TRIGGER statement fails. To see the compilation errors, run this statement:

SELECT * FROM USER_ERRORS WHERE TYPE = 'TRIGGER';

Compiled triggers depend on the schema objects on which they are defined. For example, NEW_EVALUATION_TRIGGER depends on the EVALUATIONS table:

CREATE OR REPLACE
TRIGGER NEW_EVALUATION_TRIGGER
BEFORE INSERT ON EVALUATIONS
FOR EACH ROW
BEGIN
:NEW.evaluation_id := evaluations_seq.NEXTVAL;
END;

To see the schema objects on which triggers depend, run this statement:

SELECT * FROM ALL_DEPENDENCIES WHERE TYPE = 'TRIGGER';

If an object on which a trigger depends is dropped, or changed such that there is a mismatch between the trigger and the object, then the trigger is invalidated. The next time the trigger is invoked, it is recompiled. To recompile a trigger immediately, run the ALTER TRIGGER statement with the COMPILE clause. For example:

ALTER TRIGGER NEW_EVALUATION_TRIGGER COMPILE;

See Also:

- Oracle Database PL/SQL Language Reference for more information about trigger compilation and dependencies

Dropping Triggers

You must drop a trigger before dropping the objects on which it depends.

To drop a trigger, use either the SQL Developer navigation frame and Drop tool, or the DDL statement DROP TRIGGER.

To drop a trigger using the Drop tool:

1. On the Connections tab, expand hr_conn.
Under the hr_conn icon, a list of schema object types appears.

2. Expand Triggers.
A list of triggers appears.

3. Right-click the name of the trigger to drop.
A list of choices appears.

4. Click Drop Trigger.
The Drop window opens.

5. Click Apply.
The Confirmation window opens.

6. Click OK.

See Also:

- "About Data Definition Language (DDL) Statements" for general information that applies to the DROP TRIGGER statement

- Oracle Database PL/SQL Language Reference for information about the DROP TRIGGER statement

9 Working in a Global Environment

This chapter contains the following topics:

- About Globalization Support Features

- About Initial NLS Parameter Values

- Viewing NLS Parameter Values

- Changing NLS Parameter Values

- About Individual NLS Parameters

- Using Unicode in Globalized Applications

About Globalization Support Features

Globalization support features enable you to develop multilingual applications that can be run simultaneously from anywhere in the world. An application can render the content of the user interface, and process data, using the native language and locale preferences of the user.

Note:

In the past, Oracle called globalization support National Language Support (NLS), but NLS is actually a subset of globalization support. NLS is the ability to choose a national language and store data using a specific character set. NLS is implemented with NLS parameters.

Topics:

- About Language Support

- About Territory Support

- About Date and Time Formats

- About Calendar Formats

- About Numeric and Monetary Formats

- About Linguistic Sorting and String Searching

- About Length Semantics

- About Unicode and SQL National Character Data Types

See Also:

Oracle Database Globalization Support Guide for more information about globalization support features

About Language Support

Oracle Database enables you to store, process, and retrieve data in native languages. The languages that can be stored in a database are all languages written in scripts that are encoded by Oracle-supported character sets. Through the use of Unicode databases and datatypes, Oracle Database supports most contemporary languages.

Additional support is available for a subset of the languages. The database can, for example, display dates using translated month names, and can sort text data according to cultural conventions.

In this document, the term language support refers to the additional language-dependent functionality, and not to the ability to store text of a specific language. For example, language support includes displaying dates or sorting text according to specific locales and cultural conventions. Additionally, for some supported languages, Oracle Database provides translated error messages and a translated user interface for the database utilities.

See Also:

- "About the NLS_LANGUAGE Parameter"

- Oracle Database Globalization Support Guide for a complete list of languages that Oracle Database supports

- Oracle Database Globalization Support Guide for a list of languages into which Oracle Database messages are translated

About Territory Support

Oracle Database supports cultural conventions that are specific to geographical locations. The default local time format, date format, and numeric and monetary conventions depend on the local territory setting. Setting different NLS parameters enables the database session to use different cultural settings. For example, you can set the euro (EUR) as the primary currency and the Japanese yen (JPY) as the secondary currency for a given database session, even when the territory is AMERICA.

See Also:

- "About the NLS_TERRITORY Parameter"

- Oracle Database Globalization Support Guide for a complete list of territories that Oracle Database supports

About Date and Time Formats

Different countries have different conventions for displaying the hour, day, month, and year. For example:

Country

Date Format

Example

Time Format

Example

China

yyyy-mm-dd

2005-02-28

hh24:mi:ss

13:50:23

Estonia

dd.mm.yyyy

28.02.2005

hh24:mi:ss

13:50:23

Germany

dd.mm.rr

28.02.05

hh24:mi:ss

13:50:23

UK

dd/mm/yyyy

28/02/2005

hh24:mi:ss

13:50:23

U.S.

mm/dd/yyyy

02/28/2005

hh:mi:ssxff am

1:50:23.555 PM

See Also:

- "About the NLS_DATE_FORMAT Parameter"

- "About the NLS_DATE_LANGUAGE Parameter"

- "About NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT Parameters"

- Oracle Database Globalization Support Guide for information about date/time data types and time zone support

- Oracle Database SQL Language Reference for information about date and time formats

About Calendar Formats

Oracle Database stores this calendar information for each territory:

- First day of the week

Sunday in some cultures, Monday in others. Set by the NLS_TERRITORY parameter.

- First week of the calendar year

Some countries use week numbers for scheduling, planning, and bookkeeping. In the ISO standard, this week number can differ from the week number of the calendar year. For example, 1st Jan 2005 is in ISO week number 53 of 2004. An ISO week starts on Monday and ends on Sunday. To support the ISO standard, Oracle Database provides the IW date format element, which returns the ISO week number. The first calendar week of the year is set by the NLS_TERRITORY parameter.

- Number of days and months in a year

Oracle Database supports six calendar systems in addition to the Gregorian calendar, which is the default. These additional calendar systems are:

- Japanese Imperial
Has the same number of months and days as the Gregorian calendar, but the year starts with the beginning of each Imperial Era.

- ROC Official
Has the same number of months and days as the Gregorian calendar, but the year starts with the founding of the Republic of China.

- Persian
The first six months have 31 days each, the next five months have 30 days each, and the last month has either 29 days or (in leap year) 30 days.

- Thai Buddha uses a Buddhist calendar.

- Arabic Hijrah has 12 months and 354 or 355 days.

- English Hijrah has 12 months and 354 or 355 days.

The calendar system is specified by the NLS_CALENDAR parameter.

- First year of era

The Islamic calendar starts from the year of the Hegira. The Japanese Imperial calendar starts from the beginning of an Emperor's reign (for example, 1998 is the tenth year of the Heisei era).

See Also:

- "About the NLS_TERRITORY Parameter"

- "About the NLS_CALENDAR Parameter"

- Oracle Database Globalization Support Guide for information about calendar formats

About Numeric and Monetary Formats

Different countries have different numeric and monetary conventions. For example:

Country

Numeric Format

Monetary Format

China

1,234,567.89

¥1,234.56

Estonia

1 234 567,89

1 234,56 kr

Germany

1.234.567,89

1.234,56€

UK

1,234,567.89

£1,234.56

U.S.

1,234,567.89

$1,234.56

See Also:

- "About the NLS_NUMERIC_CHARACTERS Parameter"

- "About the NLS_CURRENCY Parameter"

- "About the NLS_ISO_CURRENCY Parameter"

- "About the NLS_DUAL_CURRENCY Parameter"

- Oracle Database Globalization Support Guide for information about numeric and list parameters

- Oracle Database Globalization Support Guide for information about monetary parameters

- Oracle Database SQL Language Reference for information about number format models

About Linguistic Sorting and String Searching

Different languages have different sort orders (collating sequences). Also, different countries or cultures that use the same alphabets sort words differently. For example, in Danish, Æ is after Z, and Y and Ü are considered to be variants of the same letter.

See Also:

- "About the NLS_SORT Parameter"

- "About the NLS_COMP Parameter"

- Oracle Database Globalization Support Guide for more information about linguistic sorting and string searching

About Length Semantics

In single-byte character sets, the number of bytes and the number of characters in a string are the same. In multibyte character sets, a character or code point consists of one or more bytes. Calculating the number of characters based on byte length can be difficult in a variable-width character set. Calculating column length in bytes is called byte semantics, while measuring column length in characters is called character semantics.

Character semantics is useful for specifying the storage requirements for multibyte strings of varying widths. For example, in a Unicode database (AL32UTF8), suppose that you must have a VARCHAR2 column that can store up to five Chinese characters with five English characters. Using byte semantics, this column requires 15 bytes for the Chinese characters, which are 3 bytes long, and 5 bytes for the English characters, which are 1 byte long, for a total of 20 bytes. Using character semantics, the column requires 10 characters.

See Also:

- "About the NLS_LENGTH_SEMANTICS Parameter"

- Oracle Database Globalization Support Guide for information about character sets and length semantics

About Unicode and SQL National Character Data Types

Unicode is a character encoding system that defines every character in most of the spoken languages in the world. In Unicode, every character has a unique code, regardless of the platform, program, or language.

You can store Unicode characters in an Oracle Database in two ways:

- You can create a Unicode database that enables you to store UTF-8 encoded characters as SQL character datatypes (CHAR, VARCHAR2, CLOB, and LONG).

- You can declare columns and variables that have SQL national character datatypes.

The SQL national character data types are NCHAR, NVARCHAR2, and NCLOB. They are also called Unicode data types, because they are used only for storing Unicode data.

The national character set, which is used for all SQL national character data types, is specified when the database is created. The national character set can be either UTF8 or AL16UTF16 (default).

When you declare a column or variable of the type NCHAR or NVARCHAR2, the length that you specify is the number of characters, not the number of bytes.

See Also:

- Oracle Database Globalization Support Guide for more information about Unicode

- Oracle Database Globalization Support Guide for more information about storing Unicode characters in an Oracle Database

- Oracle Database Globalization Support Guide for more information about SQL national character data types

About Initial NLS Parameter Values

Except in SQL Developer, the initial values of NLS parameters are set by database initialization parameters. The DBA can set the values of initialization parameters in the initialization parameter file, and they take effect the next time the database is started.

In SQL Developer, the initial values of NLS parameters are as shown in Table 9-1.

Table 9-1 Initial Values of NLS Parameters in SQL Developer

Parameter

Initial Value

NLS_CALENDAR

GREGORIAN

NLS_CHARACTERSET

AL32UTF8

NLS_COMP

BINARY

NLS_CURRENCY

$

NLS_DATE_FORMAT

DD-MON-RR

NLS_DATE_LANGUAGE

AMERICAN

NLS_DUAL_CURRENCY

$

NLS_ISO_CURRENCY

AMERICA

NLS_LANGUAGE

AMERICAN

NLS_LENGTH_SEMANTICS

BYTE

NLS_NCHAR_CHARACTERSET

AL16UTF16

NLS_NCHAR_CONV_EXCP

FALSE

NLS_NUMERIC_CHARACTERS

.,

NLS_SORT

BINARY

NLS_TERRITORY

AMERICA

NLS_TIMESTAMP_FORMAT

DD-MON-RR HH.MI.SSXFF AM

NLS_TIMESTAMP_TZ_FORMAT

DD-MON-RR HH.MI.SSXFF AM TZR

NLS_TIME_FORMAT

HH.MI.SSXFF AM

NLS_TIME_TZ_FORMAT

HH.MI.SSXFF AM TZR

See Also:

Oracle Database Administrator's Guide for information about initialization parameters and initialization parameter files

Viewing NLS Parameter Values

To view the current values of NLS parameters, use the SQL Developer report National Language Support Parameters.

Note:

if you are connected to the database as the database administrator user SYS, you can use this query instead of the SQL Developer report:

SELECT * FROM V$NLS_PARAMETERS;

To view the National Language Support Parameters report:

1. In the SQL Developer window, click the tab Reports.
The Reports pane shows a list of reports.

2. Expand Data Dictionary Reports.
A list of data dictionary reports appears.

3. Expand About Your Database.
A list of reports appears.

4. Click National Language Support Parameters.
The Select Connection window opens. It has a Connection field with a drop-down menu.

5. From the drop-down menu, select hr_conn.

6. Click OK.
The Select Connection window closes and the National Language Support Parameters pane appears, showing the names of the NLS parameters and their current values.

See Also:

Oracle Database SQL Developer User's Guide for more information about SQL Developer reports

Changing NLS Parameter Values

You can change the value of one or more NLS parameters in any of these ways:

- Change the values for all SQL Developer connections, current and future.

- On the client, change the settings of the corresponding NLS environment variables.
Only on the client, the new values of the NLS environment variables override the values of the corresponding NLS parameters.

You can use environment variables to specify locale-dependent behavior for the client. For example, on a Linux system, this statement sets the value of the NLS_SORT environment variable to FRENCH, overriding the value of the NLS_SORT parameter:

% setenv NLS_SORT FRENCH

Note:

Environment variables might be platform-dependent.

- Change the values only for the current session, using an ALTER SESSION statement with this syntax:

ALTER SESSION SET parameter_name=parameter_value
[ parameter_name=parameter_value ]... ;

Only in the current session, the new values override those set in all of the preceding ways.

You can use the ALTER SESSION to test your application with the settings for different locales.

- Change the values only for the current SQL function invocation.
Only for the current SQL function invocation, the new values override those set in all of the preceding ways.

Topics:

- Changing NLS Parameter Values for All SQL Developer Connections

- Changing NLS Parameter Values for the Current SQL Function Invocation

See Also:

- Oracle Database SQL Language Reference for more information about the ALTER SESSION statement

- Oracle Database Globalization Support Guide for more information about setting NLS parameters

Changing NLS Parameter Values for All SQL Developer Connections

The following procedure shows how to change the values of NLS parameters for all SQL Developer connections, current and future.

To change National Language Support Parameter values:

1. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

2. From drop-down menu, select Preferences.
The Preferences window opens.

3. In the Preferences window, expand Database.
A list of database preferences appears.

4. Click NLS Parameters.
A list of NLS Parameters and their current values appears. The value fields are drop-down menus.

5. From the drop-down menu to the right of each parameter whose value you want to change, select the desired value.

6. Click OK.
The NLS parameters now have the values that you specified. To verify these values, see "Viewing NLS Parameter Values".

See Also:

Oracle Database SQL Developer User's Guide for more information about SQL Developer preferences

Changing NLS Parameter Values for the Current SQL Function Invocation

SQL functions whose behavior depends on the values of NLS parameters are called locale-dependent. Some locale-dependent SQL functions have optional NLS parameters. These functions are:

- TO_CHAR

- TO_DATE

- TO_NUMBER

- NLS_UPPER

- NLS_LOWER

- NLS_INITCAP

- NLSSORT

In all of the preceding functions, you can specify these NLS parameters:

- NLS_DATE_LANGUAGE

- NLS_DATE_LANGUAGE

- NLS_NUMERIC_CHARACTERS

- NLS_CURRENCY

- NLS_ISO_CURRENCY

- NLS_DUAL_CURRENCY

- NLS_CALENDAR

- NLS_SORT

In the NLSSORT function, you can also specify these NLS parameters:

- NLS_LANGUAGE

- NLS_TERRITORY

- NLS_DATE_FORMAT

To specify NLS parameters in a function, use this syntax:

'parameter=value' ['parameter=value']...

Suppose that you want NLS_DATE_LANGUAGE to be AMERICAN when this query is evaluated:

SELECT last_name FROM employees WHERE hire_date > '01-JAN-1999';

You can set NLS_DATE_LANGUAGE to AMERICAN before running the query:

ALTER SESSION SET NLS_DATE_LANGUAGE=American;
SELECT last_name FROM employees WHERE hire_date > '01-JAN-1999';

Alternatively, you can set NLS_DATE_LANGUAGE to AMERICAN inside the query, using the locale-dependent SQL function TO_DATE with its optional NLS_DATE_LANGUAGE parameter:

SELECT last_name FROM employees
WHERE hire_date > TO_DATE('01-JAN-1999', 'DD-MON-YYYY',
'NLS_DATE_LANGUAGE=AMERICAN');

Tip:

Specify optional NLS parameters in locale-dependent SQL functions only in SQL statements that must be independent of the session NLS parameter values. Using session default values for NLS parameters in SQL functions usually results in better performance.

See Also:

Oracle Database Globalization Support Guide for more information about locale-dependent SQL functions with optional NLS parameters

About Individual NLS Parameters

Topics:

- About Locale and the NLS_LANG Parameter

- About the NLS_LANGUAGE Parameter

- About the NLS_TERRITORY Parameter

- About the NLS_DATE_FORMAT Parameter

- About the NLS_DATE_LANGUAGE Parameter

- About NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT Parameters

- About the NLS_CALENDAR Parameter

- About the NLS_NUMERIC_CHARACTERS Parameter

- About the NLS_CURRENCY Parameter

- About the NLS_ISO_CURRENCY Parameter

- About the NLS_DUAL_CURRENCY Parameter

- About the NLS_SORT Parameter

- About the NLS_COMP Parameter

- About the NLS_LENGTH_SEMANTICS Parameter

See Also:

- Oracle Database Globalization Support Guide for more information about setting up a globalization support environment

- "Changing NLS Parameter Values"

About Locale and the NLS_LANG Parameter

A locale is a linguistic and cultural environment in which a system or application runs. The simplest way to specify a locale for Oracle Database software is to set the NLS_LANG parameter.

The NLS_LANG parameter sets the default values of the parameters NLS_LANGUAGE and NLS_TERRITORY for both the server session (for example, SQL statement processing) and the client application (for example, display formatting in Oracle Database tools). The NLS_LANG parameter also sets the character set that the client application uses for data entered or displayed.

The default value of NLS_LANG is set during database installation. You can use the ALTER SESSION statement to change the values of NLS parameters, including those set by NLS_LANG, for your session. However, only the client can change the NLS settings in the client environment.

See Also:

- Oracle Database Globalization Support Guide for more information about specifying a locale with the NLS_LANG parameter

- Oracle Database Globalization Support Guide for information about languages, territories, character sets, and other locale data supported by Oracle Database

- "About the NLS_LANGUAGE Parameter"

- "About the NLS_TERRITORY Parameter"

- "Changing NLS Parameter Values"

About the NLS_LANGUAGE Parameter

Specifies: Default language of the database. Default conventions for:

- Language for server messages

- Language for names and abbreviations of days and months that are specified in the SQL functions TO_CHAR and TO_DATE

- Symbols for default-language equivalents of AM, PM, AD, and BC

- Default sorting order for character data when the ORDER BY clause is specified

- Writing direction

- Affirmative and negative response strings (for example, YES and NO)

Acceptable Values: Any language name that Oracle supports. For a list, see Oracle Database Globalization Support Guide.

Default Value: Set by NLS_LANG, described in "About Locale and the NLS_LANG Parameter".

Sets default values of:

- NLS_DATE_LANGUAGE, described in "About the NLS_DATE_LANGUAGE Parameter".

- NLS_SORT, described in "About the NLS_SORT Parameter".

Example 9-1 shows how setting NLS_LANGUAGE to ITALIAN and GERMAN affects server messages and month abbreviations.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-1 NLS_LANGUAGE Affects Server Message and Month Abbreviations

1. Note the current value of NLS_LANGUAGE.

For instructions, see "Viewing NLS Parameter Values".

2. If the value in step 1 is not ITALIAN, change it:

ALTER SESSION SET NLS_LANGUAGE=ITALIAN;

3. Query a nonexistent table:

SELECT * FROM nonexistent_table;

Result:

SELECT * FROM nonexistent_table
*
ERROR at line 1:
ORA-00942: tabella o vista inesistente

4. Run this query:

SELECT LAST_NAME, HIRE_DATE
FROM EMPLOYEES
WHERE EMPLOYEE_ID IN (111, 112, 113);

Result:

LAST_NAME                 HIRE_DATE
------------------------- ---------
Sciarra                   30-SET-97
Urman                     07-MAR-98
Popp                      07-DIC-99

3 rows selected.

5. Change the value of NLS_LANGUAGE to GERMAN:

ALTER SESSION SET NLS_LANGUAGE=GERMAN;

6. Repeat the query from step 3.
Result:

SELECT * FROM nonexistent_table
*
ERROR at line 1:
ORA-00942: Tabelle oder View nicht vorhanden

7. Repeat the query from step 4.
Result:

LAST_NAME                 HIRE_DATE
------------------------- ---------
Sciarra                   30-SEP-97
Urman                     07-MRZ-98
Popp                      07-DEZ-99

3 rows selected.

8. Set NLS_LANGUAGE to the value that it had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_LANGUAGE parameter

- "About Language Support"

- "Changing NLS Parameter Values"

About the NLS_TERRITORY Parameter

Specifies: Default conventions for:

- Date format

- Timestamp format

- Decimal character and group separator

- Local currency symbol

- ISO currency symbol

- Dual currency symbol

Acceptable Values: Any territory name that Oracle supports. For a list, see Oracle Database Globalization Support Guide.

Default Value: Set by NLS_LANG, described in "About Locale and the NLS_LANG Parameter".

Sets default values of:

- NLS_DATE_FORMAT, described in "About the NLS_DATE_FORMAT Parameter".

- NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT, described in "About NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT Parameters".

- NLS_NUMERIC_CHARACTERS, described in "About the NLS_NUMERIC_CHARACTERS Parameter".

- NLS_CURRENCY, described in "About the NLS_CURRENCY Parameter".

- NLS_ISO_CURRENCY, described in "About the NLS_ISO_CURRENCY Parameter".

- NLS_DUAL_CURRENCY, described in "About the NLS_DUAL_CURRENCY Parameter".

Example 9-2 shows how setting NLS_TERRITORY to JAPAN and AMERICA affects the currency symbol.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-2 NLS_TERRITORY Affects Currency Symbol

1. Note the current value of NLS_TERRITORY.

For instructions, see "Viewing NLS Parameter Values".

2. If the value in step 1 is not JAPAN, change it:

ALTER SESSION SET NLS_TERRITORY=JAPAN;

3. Run this query:

SELECT TO_CHAR(SALARY,'L99G999D99') SALARY
FROM EMPLOYEES
WHERE EMPLOYEE_ID IN (100, 101, 102);

Result:

SALARY
--------------------
¥24,000.00
¥17,000.00
¥17,000.00

3 rows selected.

4. Change the value of NLS_TERRITORY to AMERICA:

ALTER SESSION SET NLS_TERRITORY=AMERICA;

5. Repeat the query from step 3.
Result:

SALARY
--------------------
$24,000.00
$17,000.00
$17,000.00

3 rows selected.

6. Set NLS_TERRITORY to the value that it had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_TERRITORY parameter

- "About Territory Support"

- "Changing NLS Parameter Values"

About the NLS_DATE_FORMAT Parameter

Specifies: Default date format to use with the TO_CHAR and TO_DATE functions (which are introduced in "Using Conversion Functions in Queries").

Acceptable Values: Any any valid datetime format model. For example:

NLS_DATE_FORMAT='MM/DD/YYYY'

For information about datetime format models, see Oracle Database SQL Language Reference.

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

The default date format might not correspond to the convention used in a given territory. To get dates in localized formats, you can use the 'DS' (short date) and 'DL' (long date) formats.

Example 9-3 shows how setting NLS_TERRITORY to AMERICA and FRANCE affects the default, short, and long date formats.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-3 NLS_TERRITORY Affects Date Formats

1. Note the current value of NLS_TERRITORY.

For instructions, see "Viewing NLS Parameter Values".

2. If the value in step 1 is not AMERICA, change it:

ALTER SESSION SET NLS_TERRITORY=AMERICA;

3. Run this query:

SELECT hire_date "Default",
TO_CHAR(hire_date,'DS') "Short",
TO_CHAR(hire_date,'DL') "Long"
FROM employees
WHERE employee_id IN (111, 112, 113);

Result:

Default    Short      Long
--------- ---------- -----------------------------
30-SEP-97 9/30/1997  Tuesday, September 30, 1997
07-MAR-98 3/7/1998   Saturday, March 07, 1998
07-DEC-99 12/7/1999  Tuesday, December 07, 1999

3 rows selected.

4. Change the value of NLS_TERRITORY to FRANCE:

ALTER SESSION SET NLS_TERRITORY=FRANCE;

5. Repeat the query from step 3.
Result:

Default  Short      Long
-------- ---------- ---------------------------
30/09/97 30/09/1997 tuesday 30 september 1997
07/03/98 07/03/1998 saturday 7 march 1998
07/12/99 07/12/1999 tuesday 7 december 1999

3 rows selected.

(To get the names of the days and months in French, you must set either NLS_LANGUAGE or NLS_DATE_LANGUAGE to FRENCH before running the query.)

6. Set NLS_TERRITORY to the value that it had at step 1.

Example 9-4 changes the value of NLS_DATE_FORMAT, overriding the default value set by NLS_TERRITORY.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-4 NLS_DATE_FORMAT Overrides NLS_TERRITORY

1. Note the current values of NLS_TERRITORY and NLS_DATE_FORMAT.

For instructions, see "Viewing NLS Parameter Values".

2. If the valueof NLS_TERRITORY in step 1 is not AMERICA, change it:

ALTER SESSION SET NLS_TERRITORY=AMERICA;

3. If the valueof NLS_DATE_FORMAT in step 1 is not 'Day Month ddth', change it:

ALTER SESSION SET NLS_DATE_FORMAT='Day Month ddth';

4. Run this query (from previous example, step 3):

SELECT hire_date "Default",
TO_CHAR(hire_date,'DS') "Short",
TO_CHAR(hire_date,'DL') "Long"
FROM employees
WHERE employee_id IN (111, 112, 113);

Result:

Default                  Short      Long
------------------------ ---------- -----------------------------
Tuesday   September 30th 9/30/1997  Tuesday, September 30, 1997
Saturday  March     07th 3/7/1998   Saturday, March 07, 1998
Tuesday   December  07th 12/7/1999  Tuesday, December 07, 1999

3 rows selected.

5. Set NLS_TERRITORY and NLS_DATE_FORMAT to the values that they had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_DATE_FORMAT parameter

- Oracle Database SQL Language Reference for more information about the TO_CHAR function

- Oracle Database SQL Language Reference for more information about the TO_DATE function

- "About Date and Time Formats"

- "Changing NLS Parameter Values"

About the NLS_DATE_LANGUAGE Parameter

Specifies: Language for names and abbreviations of days and months that are produced by:

- SQL functions TO_CHAR and TO_DATE (which are introduced in "Using Conversion Functions in Queries")

- Default date format (set by NLS_DATE_FORMAT, described in "About the NLS_DATE_FORMAT Parameter")

- Symbols for default-language equivalents of AM, PM, AD, and BC

Acceptable Values: Any language name that Oracle supports. For a list, see Oracle Database Globalization Support Guide.

Default Value: Set by NLS_LANGUAGE, described in "About the NLS_LANGUAGE Parameter".

Example 9-5 shows how setting NLS_DATE_LANGUAGE to FRENCH and SWEDISH affects the displayed system date.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-5 NLS_DATE_LANGUAGE Affects Displayed SYSDATE

1. Note the current value of NLS_DATE_LANGUAGE.

For instructions, see "Viewing NLS Parameter Values".

2. If the value of NLS_DATE_LANGUAGE in step 1 is not FRENCH, change it:

ALTER SESSION SET NLS_DATE_LANGUAGE=FRENCH;

3. Run this query:

SELECT TO_CHAR(SYSDATE, 'Day:Dd Month yyyy') "System Date"
FROM DUAL;

Result:

System Date
--------------------------
Mercredi:01 Octobre   2008

4. Change the value of NLS_DATE_LANGUAGE to SWEDISH:

ALTER SESSION SET NLS_DATE_LANGUAGE=SWEDISH;

5. Repeat the query from step 3.
Result:

System Date
-------------------------
Onsdag :01 Oktober   2008

6. Set NLS_DATE_LANGUAGE to the value that it had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_DATE_LANGUAGE parameter

- Oracle Database SQL Language Reference for more information about the TO_CHAR function

- Oracle Database SQL Language Reference for more information about the TO_DATE function

- "About Date and Time Formats"

- "Changing NLS Parameter Values"

About NLS_TIMESTAMP_FORMAT and NLS_TIMESTAMP_TZ_FORMAT Parameters

Specify: Default date format for:

- TIMESTAMP datatype

- TIMESTAMP WITH LOCAL TIME ZONE datatype

Acceptable Values: Any any valid datetime format model. For example:

NLS_TIMESTAMP_FORMAT='YYYY-MM-DD HH:MI:SS.FF'
NLS_TIMESTAMP_TZ_FORMAT='YYYY-MM-DD HH:MI:SS.FF TZH:TZM'

For information about datetime format models, see Oracle Database SQL Language Reference.

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_TIMESTAMP_FORMAT parameter

- Oracle Database Globalization Support Guide for more information about the NLS_TIMESTAMP_TZ_FORMAT parameter

- Oracle Database Globalization Support Guide for information about date/time data types and time zone support

- Oracle Database SQL Language Reference for more information about the TIMESTAMP datatype

- Oracle Database SQL Language Reference for more information about the TIMESTAMP WITH LOCAL TIME ZONE data type

- "About Date and Time Formats"

- "Changing NLS Parameter Values"

About the NLS_CALENDAR Parameter

Specifies: Calendar system for the database.

Acceptable Values: Any calendar system that Oracle supports. For a list, see Oracle Database Globalization Support Guide.

Default Value: Gregorian

Example 9-6 shows how setting NLS_CALENDAR to 'English Hijrah' and Gregorian affects the displayed system date.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-6 NLS_CALENDAR Affects Displayed SYSDATE

1. Note the current value of NLS_CALENDAR.

For instructions, see "Viewing NLS Parameter Values".

2. If the value of NLS_CALENDAR in step 1 is not 'English Hijrah', change it:

ALTER SESSION SET NLS_CALENDAR='English Hijrah';

3. Run this query:

SELECT SYSDATE FROM DUAL;

Result:

SYSDATE
-------------------------
29 Ramadan           1429

4. Change the value of NLS_CALENDAR to 'Gregorian':

ALTER SESSION SET NLS_CALENDAR='Gregorian';

5. Run this query:

SELECT SYSDATE FROM DUAL;

Result:

SYSDATE
---------
30-SEP-08

6. Set NLS_CALENDAR to the value that it had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_CALENDAR parameter

- "About Calendar Formats"

- "Changing NLS Parameter Values"

About the NLS_NUMERIC_CHARACTERS Parameter

Specifies: Decimal character (which separates the integer and decimal parts of a number) and group separator (which separates integer groups to show thousands and millions, for example). The group separator is the character returned by the numeric format element G.

Acceptable Values: Any two different single-byte characters except:

- A numeric character

- Plus (+)

- Minus (-)

- Less than (<)

- Greater than (>)

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

In a SQL statement, you can represent a number as either:

- Numeric literal
A numeric literal is not enclosed in quotation marks, always uses a period (.) as the decimal character, and never contains a group separator.

- Text literal
A text literal is enclosed in single quotation marks. It is implicitly or explicitly converted to a number, if required, according to the current NLS settings.

Example 9-7 shows how two different NLS_NUMERIC_CHARACTERS settings affect the displayed result of the same query.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-7 NLS_NUMERIC_CHARACTERS Affects Decimal Character and Group Separator

1. Note the current value of NLS_NUMERIC_CHARACTERS.

For instructions, see "Viewing NLS Parameter Values".

2. If the value of NLS_NUMERIC_CHARACTERS in step 1 is not ",." (decimal character is comma and group separator is period), change it:

ALTER SESSION SET NLS_NUMERIC_CHARACTERS=",.";

3. Run this query:

SELECT TO_CHAR(4000, '9G999D99') "Number" FROM DUAL;

Result:

Number
---------
4.000,00

4. Change the value of NLS_NUMERIC_CHARACTERS to ",." (decimal character is period and group separator is comma):

ALTER SESSION SET NLS_NUMERIC_CHARACTERS=".,";

5. Run this query:

SELECT TO_CHAR(4000, '9G999D99') "Number" FROM DUAL;

Result:

Number
---------
4,000.00

6. Set NLS_NUMERIC_CHARACTERS to the value that it had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_NUMERIC_CHARACTERS parameter

- "About Numeric and Monetary Formats"

- "Changing NLS Parameter Values"

About the NLS_CURRENCY Parameter

Specifies: Local currency symbol (the character string returned by the numeric format element L).

Acceptable Values: Any valid currency symbol string.

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

Example 9-8 changes the value of NLS_CURRENCY, overriding the default value set by NLS_TERRITORY.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-8 NLS_CURRENCY Overrides NLS_TERRITORY

1. Note the current values of NLS_TERRITORY and NLS_CURRENCY.

For instructions, see "Viewing NLS Parameter Values".

2. If the valueof NLS_TERRITORY in step 1 is not AMERICA, change it:

ALTER SESSION SET NLS_TERRITORY=AMERICA;

3. Run this query:

SELECT TO_CHAR(salary, 'L099G999D99') "Salary"
FROM EMPLOYEES
WHERE salary > 13000;

Result:

Salary
---------------------
$024,000.00
$017,000.00
$017,000.00
$014,000.00
$013,500.00

4. Change the value of NLS_CURRENCY to '¥':

ALTER SESSION SET NLS_CURRENCY='¥';

5. Run this query:

SELECT TO_CHAR(salary, 'L099G999D99') "Salary"
FROM EMPLOYEES
WHERE salary > 13000;

Result:

Salary
---------------------
¥024,000.00
¥017,000.00
¥017,000.00
¥014,000.00
¥013,500.00

6. Set NLS_TERRITORY and NLS_CURRENCY to the values that they had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_CURRENCY parameter

- "About Numeric and Monetary Formats"

- "Changing NLS Parameter Values"

About the NLS_ISO_CURRENCY Parameter

Specifies: ISO currency symbol (the character string returned by the numeric format element C).

Acceptable Values: Any valid currency symbol string.

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

Local currency symbols can be ambiguous, but ISO currency symbols are unique.

Example 9-9 shows that the territories AUSTRALIA and AMERICA have the same local currency symbol, but different ISO currency symbols.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-9 NLS_ISO_CURRENCY

1. Note the current values of NLS_TERRITORY and NLS_ISO_CURRENCY.

For instructions, see "Viewing NLS Parameter Values".

2. If the value of NLS_TERRITORY in step 1 is not AUSTRALIA, change it:

ALTER SESSION SET NLS_TERRITORY=AUSTRALIA;

3. Run this query:

SELECT TO_CHAR(salary, 'L099G999D99') "Local",
TO_CHAR(salary, 'C099G999D99') "ISO"
FROM EMPLOYEES
WHERE salary > 15000;

Result:

Local                 ISO
--------------------- ------------------
$024,000.00      AUD024,000.00
$017,000.00      AUD017,000.00
$017,000.00      AUD017,000.00

4. Change the value of NLS_TERRITORY to AMERICA:

ALTER SESSION SET NLS_TERRITORY=AMERICA;

5. Run this query:

SELECT TO_CHAR(salary, 'L099G999D99') "Local",
TO_CHAR(salary, 'C099G999D99') "ISO"
FROM EMPLOYEES
WHERE salary > 15000;

Result:

Local                 ISO
--------------------- ------------------
$024,000.00      USD024,000.00
$017,000.00      USD017,000.00
$017,000.00      USD017,000.00

6. Set NLS_TERRITORY and NLS_ISO_CURRENCY to the values that they had at step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_ISO_CURRENCY parameter

- "About Numeric and Monetary Formats"

- "Changing NLS Parameter Values"

About the NLS_DUAL_CURRENCY Parameter

Specifies: Dual currency symbol (introduced to support the euro currency symbol during the euro transition period).

Acceptable Values: Any valid currency symbol string.

Default Value: Set by NLS_TERRITORY, described in "About the NLS_TERRITORY Parameter".

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_DUAL_CURRENCY parameter

- "About Numeric and Monetary Formats"

- "Changing NLS Parameter Values"

About the NLS_SORT Parameter

Specifies: Linguistic sort order (collating sequence) for queries that have the ORDER BY clause.

Acceptable Values:

- BINARY
Sort order is based on the binary sequence order of either the database character set or the national character set, depending on the data type.

- Any linguistic sort name that Oracle supports
Sort order is based on the order of the specified linguistic sort name. The linguistic sort name is usually the same as the language name, but not always. For a list of supported linguistic sort names, see Oracle Database Globalization Support Guide.

Default Value: Set by NLS_LANGUAGE, described in "About the NLS_LANGUAGE Parameter".

Example 9-10 shows how two different NLS_SORT settings affect the displayed result of the same query. The settings are BINARY and Traditional Spanish (SPANISH_M). Traditional Spanish treats ch, ll, and ñ as letters that follow c, l, and n, respectively.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-10 NLS_SORT Affects Linguistic Sort Order

1. Create table for Spanish words:

CREATE TABLE temp (name VARCHAR2(15));

2. Populate table with some Spanish words:

INSERT INTO temp (name) VALUES ('laguna');
INSERT INTO temp (name) VALUES ('llama');
INSERT INTO temp (name) VALUES ('loco');

3. Note the current value of NLS_SORT.

For instructions, see "Viewing NLS Parameter Values".

4. If the valueof NLS_SORT in step 3 is not BINARY, change it:

ALTER SESSION SET NLS_SORT=BINARY;

5. Run this query:

SELECT * FROM temp ORDER BY name;

Result:

NAME
---------------
laguna
llama
loco

6. Change the value of NLS_SORT to SPANISH_M (Traditional Spanish):

ALTER SESSION SET NLS_SORT=SPANISH_M;

7. Repeat the query from step 5.
Result:

NAME
---------------
laguna
loco
llama

8. Drop the table:

DROP TABLE temp;

9. Set NLS_SORT to the value that it had at step 3.

Case-Insensitive and Accent-Insensitive Sorts

Operations inside Oracle Database are sensitive to the case and the accents of the characters. To perform a case-insensitive sort, append _CI to the value of the NLS_SORT parameter (for example, BINARY_CI or XGERMAN_CI). To perform a sort that is both case-insensitive and accent-insensitive, append _AI to the value of the NLS_SORT parameter (for example, BINARY_AI or FRENCH_M_AI).

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_SORT parameter

- Oracle Database Globalization Support Guide for more information about case-insensitive and accent-insensitive sorts

- "About Linguistic Sorting and String Searching"

- "Changing NLS Parameter Values"

About the NLS_COMP Parameter

Specifies: Character comparison behavior of SQL operations.

Acceptable Values:

- BINARY
SQL compares the binary codes of characters. One character is greater than another if it has a higher binary code.

- LINGUISTIC
SQL performs a linguistic comparison based on the value of the NLS_SORT parameter, described in "About the NLS_SORT Parameter".

- ANSI
This value is provided only for backward compatibility.

Default Value: BINARY

Example 9-11 shows that the result of a query can depend on the NLS_COMP setting.

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-11 NLS_COMP Affects SQL Character Comparison

1. Note the current values of NLS_SORT and NLS_COMP.

For instructions, see "Viewing NLS Parameter Values".

2. If the values of NLS_SORT and NLS_COMP in step 1 are not SPANISH_M (Traditional Spanish) and BINARY, respectively, change them:

ALTER SESSION SET NLS_SORT=SPANISH_M NLS_COMP=BINARY;

3. *Run this query:

SELECT LAST_NAME FROM EMPLOYEES
WHERE LAST_NAME LIKE 'C%';

Result:

LAST_NAME
-------------------------
Cabrio
Cambrault
Cambrault
Chen
Chung
Colmenares

6 rows selected

4. Change the value of NLS_COMP to LINGUISTIC:

ALTER SESSION SET NLS_COMP=LINGUISTIC;

5. Repeat the query from step 3.
Result:

LAST_NAME
-------------------------
Cabrio
Cambrault
Cambrault
Colmenares

4 rows selected

This time, Chen and Chung are not returned because Traditional Spanish treats ch as a single character that follows c.

6. Set NLS_SORT and NLS_COMP to the values that they had in step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_COMP parameter

- "About Linguistic Sorting and String Searching"

- "Changing NLS Parameter Values"

About the NLS_LENGTH_SEMANTICS Parameter

Specifies: Length semantics for columns of the character data types CHAR, VARCHAR2, and LONG; that is, whether these columns are specified in bytes or in characters. (Applies only to columns that are declared after the parameter is set.)

Acceptable Values:

- BYTE
New CHAR, VARCHAR2, and LONG columns are specified in bytes.

- CHAR
New CHAR, VARCHAR2, and LONG columns are specified in characters.

Default Value: BYTE

To try this example in SQL Developer, enter the statements and queries in the SQL Worksheet. For information about the SQL Worksheet, see "Running Queries in SQL Developer". The results shown here are from SQL*Plus; their format is slightly different in SQL Developer.

Example 9-12 NLS_LENGTH_SEMANTICS Affects Storage of VARCHAR2 Column

1. Note the current values of NLS_LENGTH_SEMANTICS.

For instructions, see "Viewing NLS Parameter Values".

2. If the value of NLS_LENGTH_SEMANTICS in step 1 is not BYTE, change it:

ALTER SESSION SET NLS_LENGTH_SEMANTICS=BYTE;

3. Create a table with a VARCHAR2 column:

CREATE TABLE SEMANTICS_BYTE(SOME_DATA VARCHAR2(20));

4. Click the tab Connections.
The Connections pane shows the connection hr_conn.

5. Expand hr_conn.
A list of schema object types appears, including Tables.

6. Expand Tables.
A list of tables appears, including SEMANTICS_BYTE.

7. Select SEMANTICS_BYTE.
To the right of the Connections pane, the Columns pane shows that for Column Name SOME_DATA, the Data Type is VARCHAR2(20 BYTE).

8. Change the value of NLS_LENGTH_SEMANTICS to CHAR:

ALTER SESSION SET NLS_LENGTH_SEMANTICS=CHAR;

9. Create another table with a VARCHAR2 column:

CREATE TABLE SEMANTICS_CHAR(SOME_DATA VARCHAR2(20));

10. In the Connections pane, click the Refresh icon.
The list of tables now includes SEMANTICS_CHAR.

11. Select SEMANTICS_CHAR.
The Columns pane shows that for Column Name SOME_DATA, the Data Type is VARCHAR2(20 CHAR).

12. Select SEMANTICS_BYTE again.
The Columns pane shows that for Column Name SOME_DATA, the Data Type is still VARCHAR2(20 BYTE).

13. Set the value of NLS_LENGTH_SEMANTICS to the value that it had in step 1.

See Also:

- Oracle Database Globalization Support Guide for more information about the NLS_LENGTH_SEMANTICS parameter

- "About Length Semantics"

- "Changing NLS Parameter Values"

Using Unicode in Globalized Applications

You can insert and retrieve Unicode data. Data is transparently converted among the database and client programs, which ensures that client programs are independent of the database character set and national character set.

Topics:

- Representing Unicode String Literals in SQL and PL/SQL

- Avoiding Data Loss During Character-Set Conversion

See Also:

- Oracle Database Globalization Support Guide for more information about SQL and PL/SQL programming with Unicode

- Oracle Database Globalization Support Guide for general information about programming with Unicode

Representing Unicode String Literals in SQL and PL/SQL

There are three ways to represent a Unicode string literal in SQL or PL/SQL:

- N'string'
Example: N'résumé'.

Limitations: See "Avoiding Data Loss During Character-Set Conversion".

- NCHR(number)
The SQL function NCHR returns the character whose binary equivalent is number in the national character set. The character returned has data type NVARCHAR2.

Example: NCHR(36) represents $ in the default national character set, AL16UTF16.

Limitations: Portability of the value of NCHR(number) is limited to applications that use the same national character set.

- UNISTR('string')
The SQL function UNISTR converts string to the national character set.

For portability and data preservation, Oracle recommends that string contain only ASCII characters and Unicode encoding values. A Unicode encoding value has the form \xxxx, where xxxx is the hexadecimal value of a character code value in UCS-2 encoding format.

Example: UNISTR('G\0061ry') represents 'Gary'

ASCII characters are converted to the database character set and then to the national character set. Unicode encoding values are converted directly to the national character set.

See Also:

- Oracle Database Globalization Support Guide for more information about Unicode string literals

- Oracle Database SQL Language Reference for more information about the NCHR function

- Oracle Database SQL Language Reference for more information about the UNISTR function

Avoiding Data Loss During Character-Set Conversion

As part of a SQL or PL/SQL statement, a literal (with or without the prefix N) is encoded in the same character set as the rest of the statement. On the client side, the statement is encoded in the client character set, which is determined by the NLS_LANG parameter. On the server side, the statement is encoded in the database character set.

When the SQL or PL/SQL statement is transferred from the client to the database, its character set is converted accordingly. If the database character set does not contain all characters that the client used in the text literals, then data is lost in this conversion. NCHAR string literals are more vulnerable than CHAR text literals, because they are designed to be independent of the database character set.

To avoid data loss in conversion to an incompatible database character set, you can activate the NCHAR literal replacement functionality. For more information, see Oracle Database Globalization Support Guide.

10 Deploying an Oracle Database Application

This chapter contains the following topics:

- About Deployment Environments

- About Installation Script Files

- Creating Installation Script Files

- Installing the Sample Application

- Checking the Validity of an Installation

- Archiving the Installation Script Files

About Deployment Environments

Deployment is installing your application in one or more environments where other users can run it.

The schema in which you develop your application is called the development environment. (The development environment for the sample application is the sample schema HR.) The other environments in which you deploy your application are called deployment environments. These environments might exist in your organization; if not, you can create them.

The first deployment environment is the test environment. In the test environment, you can thoroughly test the functionality of the application, determine whether it is packaged correctly, and fix any problems before deploying it in the production environment.

You might also deploy your application to an education environment, either before or after deploying it to the production environment. An education environment provides a place for users to practice running the application without affecting other environments.

About Installation Script Files

To deploy an application, you run one or more installation script files. If these files do not exist, you can create them, with SQL Developer or any text editor.

An installation script file is an executable file (.sql file) that contains an installation script. An installation script is composed ot DDL statements, INSERT statements, or both. When you run your installation script files, the DDL statements create the schema objects of your application in the deployment environment, and the INSERT statements insert the data from the tables in your development environment (the source tables) into the corresponding tables in the deployment environment (the new tables).

Topics:

- About DDL Statements and Schema Object Dependencies

- About INSERT Statements and Constraints

About DDL Statements and Schema Object Dependencies

When you run your installation script files, their DDL statements create the schema objects of your application in the deployment environment. To create the installation script files correctly and run them in the correct order, you must understand the dependencies between the schema objects of your application.

If the definition of object A references object B, then A depends on B. Therefore, you must create B before you create A. Otherwise, the statement that creates B either fails or creates B in an invalid state, depending on the object type.

Typically, you install schema objects and data in the deployment environment in this order:

1. Package specifications

2. Tables (with constraints and indexes) in correct order

3. Sequences (often used by triggers)

4. Triggers

5. Synonyms

6. Views (which might reference functions, procedures, or synonyms)

7. Package bodies

8. Data

However, for a complex application, the order for creating the objects is rarely obvious. Usually, you must consult the database designer or a diagram of the design.

See Also:

- Oracle Database Advanced Application Developer's Guide for more information about schema object dependencies

- "About Data Definition Language (DDL) Statements"

About INSERT Statements and Constraints

When you run your installation script files, their INSERT statements insert the data from the source tables into the corresponding new tables. For each source table in your application, you must determine whether any constraints could be violated when their data is inserted in the new table. If so, you must first disable those constraints, then insert the data, and then try to re-enable the constraints. If a data item violates a constraint, you cannot re-enable that constraint until you correct the data item.

If you are simply inserting lookup data in correct order, constraints are not violated. Therefore, you do not need to disable them first.

If you are inserting data from an outside source (such as a file, spreadsheet, or older application), or from many tables that have much dependent data, disable the constraints before inserting the data.

Some possible ways to disable and re-enable the constraints are:

- Using SQL Developer, disable and re-enable the constraints one at a time.

- Edit the installation script file, adding SQL statements that disable and re-enable each constraint.

- Create a SQL script with SQL statements that disable and enable each constraint.

- Find the constraints in the Oracle Database data dictionary, and create a SQL script with the SQL statements to disable and enable each constraint.
To find and enable the constraints used in the EVALUATIONS, PERFORMANCE_PARTS, and SCORES tables, enter these statements into a SQL Worksheet window:

SELECT 'ALTER TABLE '|| TABLE_NAME || ' DISABLE CONSTRAINT '||
CONSTRAINT_NAME ||';'
FROM user_constraints
WHERE table_name IN ('EVALUATIONS','PERFORMANCE_PARTS','SCORES');

SELECT 'ALTER TABLE '|| TABLE_NAME || ' ENABLE CONSTRAINT '||
CONSTRAINT_NAME ||';'
FROM user_constraints
WHERE table_name IN ('EVALUATIONS','PERFORMANCE_PARTS','SCORES');

See Also:

- "About the INSERT Statement"

- "Ensuring Data Integrity in Tables"

Creating Installation Script Files

This topic explains how to use SQL Developer to create an installation script file, when and how to edit installation script files that create sequences and triggers, and how to create installation script files for the schema objects and data of the sample application.

The tutorials in this topic assume that you created the objects in the sample schema HR, using the instructions in this document, and are deploying the sample application in another standard HR schema.

Note:

To do the tutorials in this document, you must be connected to Oracle Database as the user HR from SQL Developer. For instructions, see "Connecting to Oracle Database as User HR from SQL Developer".

Topics:

- Creating an Installation Script File with SQL Developer

- Editing Installation Script Files that Create Sequences

- Editing Installation Script Files that Create Triggers

- Tutorial: Creating an Installation Script File for the Sequence and Tables

- Tutorial: Creating an Installation Script File for the Package

- Tutorial: Creating an Installation Script File for the Synonym and View

- Tutorial: Creating an Installation Script File for the Data

Creating an Installation Script File with SQL Developer

To create an installation script file with SQL Developer, use the Database Export tool. You specify the name of the installation script file and the objects and data to export, and SQL Developer generates DDL statements for creating the objects and INSERT statements for inserting the data into new tables, and writes these statements to the installation script file.

Note:

In the following procedure, you might have to enlarge the SQL Developer windows to see all fields and options.

To create an installation script file with the Database Export tool:

1. If you have not done so, create a directory for the installation script file, separate from the Oracle Database installation directory (for example, C:\my_exports).

2. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

3. From drop-down menu, select Database Export.
The Source/Destination window opens.

4. In the Source/Destination window:

1. In the File field, type the full path name of the installation script file (for example, C:\my_exports\hr_export.sql).
The file name must end with .sql.

2. From the Connections drop-down menu, select your connection (for example, hr_conn).

3. Select the desired DDL Options (and deselect any selected undesired options).
By default, Terminator and Pretty Print are selected and all other options are deselected. If you deselect Terminator, the installation script file fails.

For descriptions of the DDL Options, see Oracle Database SQL Developer User's Guide.

4. Click Next.

The Types to Export window appears, listing the types of objects, and data, that you can export. To the left of each object is a check box. By default, every check box is selected.

5. In the Types to Export window:

1. Deselect the check boxes for the types that you do not want to export.
Selecting or deselecting Toggle All selects or deselects all check boxes.

2. If you do not want to export data, deselect the check box Data.

3. Click Next.

The Specify Objects window appears.

6. In the Specify Objects window:

1. In the drop-down menu with the value HR, accept that value.

2. Click Go.
A list appears, showing all objects in schema HR whose types you specified in step 5, and, if you specified Data in step 5, names of tables in schema HR.

3. To export all items on the list, click >>; otherwise, select the objects to export and the tables with data to export, and click >.
The items to be exported move from the original column to the other column. (To move all of them back to the original column, click <<; to move individual items back, select them and click <.)

4. Click Next.

The Export Summary window appears.

7. In the Export Summary window, click Finish.

The Exporting window opens, showing that exporting is occurring. When exporting is complete, the Exporting window closes, and the SQL Worksheet shows the contents of the installation script file that you specified in step 4.

8. In the installation script file, check that:

- Referenced objects are created before their dependent objects.

- Tables are created before data is inserted into them.

If necessary, edit the file in the SQL Worksheet or any text editor.

See Also:

- "About Data Definition Language (DDL) Statements"

- "About the INSERT Statement"

- Oracle Database SQL Developer User's Guide for more information about SQL Developer dialog boxes

- Oracle Database Advanced Application Developer's Guide for information about schema object dependencies

- "Tutorial: Creating an Installation Script File for the Sequence and Tables"

- "Tutorial: Creating an Installation Script File for the Package"

- "Tutorial: Creating an Installation Script File for the Synonym and View"

- "Tutorial: Creating an Installation Script File for the Data"

Editing Installation Script Files that Create Sequences

For a sequence, SQL Developer generates a CREATE SEQUENCE statement whose START WITH value is relative to the current value of the sequence in the development environment.

If your application uses the sequence to generate unique keys, and you will not insert the data from the source tables into the corresponding new tables, then you might want to edit the START WITH value in the installation script file. You can edit the installation script file in the SQL Worksheet or any text editor.

See Also:

"Tutorial: Creating a Sequence"

Editing Installation Script Files that Create Triggers

If your application has a BEFORE INSERT trigger on a source table, and you will insert the data from that source table into the corresponding new table, then you must decide if you want the trigger to fire before each INSERT statement in the installation script file inserts data into the new table.

For example, in the sample application, NEW_EVALUATION_TRIGGER fires before a row is inserted into the EVALUATIONS table, and generates the unique number for the primary key of that row, using EVALUATIONS_SEQ. The trigger fires once for each row affected by the triggering INSERT statement. (NEW_EVALUATION_TRIGGER is created in "Tutorial: Creating a Trigger that Generates a Primary Key for a Row Before It Is Inserted".)

The source EVALUATIONS table is populated with primary keys. If you do not want the installation script to put new primary key values in the new EVALUATIONS table, then you must edit the CREATE TRIGGER statement in the installation script file as shown in bold:

CREATE OR REPLACE
TRIGGER NEW_EVALUATION_TRIGGER
BEFORE INSERT ON EVALUATIONS
FOR EACH ROW
BEGIN
IF :NEW.evaluation_id IS NULL THEN
:NEW.evaluation_id := evaluations_seq.NEXTVAL
END IF;
END;

Also, check the current value of the sequence. If it not is greater than the maximum value in the primary key column, make it greater.

You can edit the installation script file in the SQL Worksheet or any text editor.

Two alternatives to editing the installation script file are:

- Change the trigger definition in the source file and then re-create the installation script file.
For information about changing triggers, see "Changing Triggers".

- Disable the trigger before running the data installation script file, and then re-enable it afterward.
For information about disabling and enabling triggers, see "Disabling and Enabling Triggers".

See Also:

"Creating Triggers"

Tutorial: Creating an Installation Script File for the Sequence and Tables

This tutorial shows how to use the SQL Developer tool Database Export to create an installation script file for the tables and sequence of the sample application, including the constraints, indexes, and triggers associated with the tables.

Note:

In the following procedure, you might have to enlarge the SQL Developer windows to see all fields and options.

To create an installation script file for the tables and sequence:

1. If you have not done so, create the directory C:\my_exports.

2. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

3. From drop-down menu, select Database Export.
The Source/Destination window opens.

4. In the Source/Destination window:

1. In the File field, type: C:\my_exports\2day_tables.sql.

2. From the Connections drop-down menu, select hr_conn.

3. Accept the default DDL Options, Terminator and Pretty Print.

4. Click Next.

The Types to Export window appears.

5. In the Types to Export window:

1. Deselect all check boxes except Tables, Sequences, Indexes, Constraints, and Triggers.

2. Click Next.

The Specify Objects window appears.

6. In the Specify Objects window:

1. In the drop-down menu with the value HR, accept that value.

2. In the drop-down menu with the value All, select the value TABLE.

3. Click Go.
A list of the tables in schema HR appears.

4. Select HR.PERFORMANCE_PARTS, HR.EVALUATIONS, HR.SCORES, and HR.EVALUATIONS_LOG.

5. Click >.
The selected tables move from the original column to the other column.

6. In the drop-down menu with the value TABLE, select the value SEQUENCE.

7. Click Go.
A list of the sequences in schema HR appears.

8. Select HR.EVALUATIONS_SEQ.

9. Click >.
HR.EVALUATIONS_SEQ moves from the original column to the other column.

10. (Optional) In the drop-down menu with the value SEQUENCE, select the value All.
HR.PERFORMANCE_PARTS, HR.EVALUATIONS, HR.SCORES, HR.EVALUATIONS_LOG and HR.EVALUATIONS_SEQ show.

11. Click Next.

The Export Summary window appears.

7. In the Export Summary window, click Finish.
The Exporting window opens, showing that exporting is occurring. When exporting is complete, the Exporting window closes, and the SQL Worksheet shows the contents of the file C:\my_exports\2day_tables.sql.

8. In the installation script file, C:\my_exports\2day_tables.sql, check that referenced objects are created before their dependent objects:

- The sequence EVALUATIONS_SEQ must be created before the table EVALUATIONS, because EVALUATIONS has a trigger, NEW_EVALUATION_TRIGGER, that uses EVALUATIONS_SEQ.

- The table EVALUATIONS_LOG must be created before the table EVALUATIONS, because EVALUATIONS has a trigger, EVAL_CHANGE_TRIGGER, that uses EVALUATIONS_LOG.

- The tables EVALUATIONS and PERFORMANCE_PARTS must be created before the table SCORES, because SCORES has foreign keys to both EVALUATIONS and PERFORMANCE_PARTS.

If necessary, edit the file in the SQL Worksheet or any text editor.

See Also:

- "Creating Tables"

- "Tutorial: Creating a Sequence"

- "Creating an Installation Script File with SQL Developer"

Tutorial: Creating an Installation Script File for the Package

This tutorial shows how to use the SQL Developer tool Database Export to create an installation script file for the package (specification and body) of the sample application.

Note:

In the following procedure, you might have to enlarge the SQL Developer windows to see all fields and options.

To create an installation script file for the package:

1. If you have not done so, create the directory C:\my_exports.

2. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

3. From drop-down menu, select Database Export.
The Source/Destination window opens.

4. In the Source/Destination window:

1. In the File field, type: C:\my_exports\2day_package.sql.

2. From the Connections drop-down menu, select hr_conn.

3. Accept the default DDL Options, Terminator and Pretty Print.

4. Click Next.

The Types to Export window appears.

5. In the Types to Export window:

1. Deselect all check boxes except Package Spec and Package Body.

2. Click Next.

The Specify Objects window appears.

6. In the Specify Objects window:

1. In the drop-down menu with the value HR, accept that value.

2. In the drop-down menu with the value All, accept that value.

3. Click Go.
A list of the packages and package bodies in schema HR appears.

4. If the only items listed are the package HR.EMP_EVAL and the package body HR.EMP_EVAL, click >>; otherwise, select those two items from the list and click >.
The package HR.EMP_EVAL and the package body HR.EMP_EVAL move from the original column to the other column.

5. Click Next.

The Export Summary window appears.

7. In the Export Summary window, click Finish.
The Exporting window opens, showing that exporting is occurring. When exporting is complete, the Exporting window closes, and the SQL Worksheet shows the contents of the installation script file that you specified in step 4.

See Also:

- "Tutorial: Creating a Package Specification"

- "Tutorial: Creating a Package Body"

- "Creating an Installation Script File with SQL Developer"

Tutorial: Creating an Installation Script File for the Synonym and View

This tutorial shows how to use the SQL Developer tool Database Export to create an installation script file for the synonym and view of the sample application.

Note:

In the following procedure, you might have to enlarge the SQL Developer windows to see all fields and options.

To create an installation script file for the synonym and view:

1. If you have not done so, create the directory C:\my_exports.

2. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

3. From drop-down menu, select Database Export.
The Source/Destination window opens.

4. In the Source/Destination window:

1. In the File field, type: C:\my_exports\2day_other.sql.

2. From the Connections drop-down menu, select hr_conn.

3. Accept the default DDL Options, Terminator and Pretty Print.

4. Click Next.

The Types to Export window appears.

5. In the Types to Export window:

1. Deselect all check boxes except Views and Synonyms.

2. Click Next.

The Specify Objects window appears.

6. In the Specify Objects window:

1. In the drop-down menu with the value HR, accept that value.

2. In the drop-down menu with the value All, select the value VIEW.

3. Click Go.
A list of the views in schema HR appears.

4. Select HR.EMP_LOCATIONS.

5. Click >.
HR.EMP_LOCATIONS moves from the original column to the other column.

6. In the drop-down menu with the value VIEW, select the value SYNONYM.

7. Click Go.
A list of the synonyms in schema HR appears.

8. Select HR.EMP.

9. Click >.
HR.EMP moves from the original column to the other column.

10. (Optional) In the drop-down menu with the value SYNONYM, select the value All.
HR.EMP_LOCATIONS and HR.EMP show.

11. Click Next.

The Export Summary window appears.

7. In the Export Summary window, click Finish.
The Exporting window opens, showing that exporting is occurring. When exporting is complete, the Exporting window closes, and the SQL Worksheet shows the contents of the file C:\my_exports\2day_other.sql.

See Also:

- "Creating Views"

- "Creating Synonyms"

- "Creating an Installation Script File with SQL Developer"

Tutorial: Creating an Installation Script File for the Data

This tutorial shows how to use the SQL Developer tool Database Export to create an installation script file for the data of the sample application. If you followed the instructions in this document, you added data only to the table PERFORMANCE_PARTS.

Note:

In the following procedure, you might have to enlarge the SQL Developer windows to see all fields and options.

To create an installation script file for the data:

1. If you have not done so, create the directory C:\my_exports.

2. In the SQL Developer window, click the menu Tools.
A drop-down menu appears.

3. From drop-down menu, select Database Export.
The Source/Destination window opens.

4. In the Source/Destination window:

1. In the File field, type: C:\my_exports\2day_data.sql.

2. From the Connections drop-down menu, select hr_conn.

3. Accept the default DDL Options, Terminator and Pretty Print.

4. Click Next.

The Types to Export window appears.

5. In the Types to Export window:

1. Deselect all check boxes except Data.

2. Click Next.

The Specify Data window appears.

6. In the Specify Data window:

1. In the drop-down menu with the value HR, accept that value.

2. Click Go.
A list of the tables in schema HR appears.

3. Select HR.PERFORMANCE_PARTS.

4. Click >.
HR.PERFORMANCE_PARTS moves from the original column to the other column.

5. Click Next.

The Export Summary window appears.

7. In the Export Summary window, click Finish.
The Exporting window opens, showing that exporting is occurring. When exporting is complete, the Exporting window closes, and the SQL Worksheet shows the contents of the file C:\my_exports\2day_data.sql.

See Also:

- "About the INSERT Statement"

- "Creating an Installation Script File with SQL Developer"

Installing the Sample Application

To install the sample application, you run the installation script files that you created in the tutorials in "Creating Installation Script Files", in this order:

1. 2day_tables.sql

2. 2day_package.sql

3. 2day_other.sql

4. 2day_data.sql

You can either run the files one at a time, or you can create and run a master SQL script file that runs them in order.

The following master SQL script runs the files in order, commits the changes, and writes server messages to a log file:

spool C:\my_exports\create_log.txt
@C:\my_exports\2day_tables.sql
@C:\my_exports\2day_package.sql
@C:\my_exports\2day_other.sql
@C:\my_exports\2day_data.sql
commit;
spool off

The SQL*Plus command @file_name.sql runs a file.

Typically, you run the master script file in SQL*Plus. However, if the master script specifies the full path names of the individual files (as in the preceding example), you can run it in SQL Developer.

The following procedure uses SQL Developer to install the sample application by running the installation script files one at a time, in order.

Note:

The deployment environment must be different from the development environment, and is assumed to be another standard HR schema.

To install the sample application using SQL Developer:

1. Connect to Oracle Database as user HR in the deployment environment.

For instructions, see "Connecting to Oracle Database as User HR from SQL Developer". For Connection Name, enter a name other than hr_conn (for example, hr_conn_2).

2. In the navigation frame, click the tab Files.
The Files pane appears, showing the directories on your computer.

3. Navigate to the directory C:\my_exports.

4. Expand my_exports.
The list of installation script files appears.

5. Right-click 2day_tables.sql.

A list of choices appears.

6. Select Open.
In the SQL Worksheet, a new 2day_tables.sql pane appears, showing the content of the 2day_tables.sql file.

7. Click the icon Run Script.
The Select Connection window opens.

8. For Connection, on the drop-down menu, select the connection to the deployment environment (created in step 1).

9. Click OK.
The result of each statement in 2day_tables.sql is displayed in the Script Output pane.

10. Click the icon Clear.

The title of the 2day_tables.sql pane is now in italic font, indicating that the changes have not been committed, and the SQL Worksheet is blank.

11. Repeat steps 5 through 10 for 2day_package.sql.

12. Repeat steps 5 through 10 for 2day_other.sql.

13. Repeat steps 5 through 10 for 2day_data.sql.

14. Click the icon Commit.
The changes are committed.

When you are sure that the individual installation script files run without errors, you can create a master SQL script (.sql) file that runs them in order, commits the changes, and writes the results to a log file. For example:

spool C:\my_exports\create_log.txt
@C:\my_exports\2day_tables.sql
@C:\my_exports\2day_package.sql
@C:\my_exports\2day_other.sql
@C:\my_exports\2day_data.sql
commit;
spool off

Typically, you run the master file in SQL*Plus. However, if the master file specifies the full path names of the individual files (as in the preceding example), you can open and run it in SQL Developer.

See Also:

- Oracle Database SQL Developer User's Guide for more information about running scripts in SQL Developer

- SQL*Plus User's Guide and Reference for more information about using scripts in SQL*Plus

Checking the Validity of an Installation

After installing your application in a deployment environment, you can check its validity in the following ways in SQL Developer:

- In the Connections pane:

1. Expand the connection to the deployment environment.

2. Examine the definitions of the new objects.

- In the Reports pane:

1. Expand Data Dictionary Reports.
A list of data dictionary reports appears.

2. Expand All Objects.
A list of objects reports appears.

3. Select All Objects.

4. Click the icon Run Report.
The Enter Bind Values window appears.

5. Select either Owner or Object.

6. Click Apply.
The message "Executing Report" shows, followed by the report itself.

For each object, this report lists the Owner, Object Type, Object Name, Status (Valid or Invalid), Date Created, and Last DDL. Last DDL is the date of the last DDL operation that affected the object.

7. Select Invalid Objects.
The Enter Bind Values window appears.

8. Click Apply.
The message "Executing Report" shows, followed by the report itself.

For each object whose Status is Invalid, this report lists the Owner, Object Type, and Object Name.

See Also:

Oracle Database SQL Developer User's Guide for more information about SQL Developer reports

Archiving the Installation Script Files

After verifying that the installation of your application is valid, you might want to archive your installation script files in a source code control system. Before doing so, add comments to each file, documenting its creation date and purpose. If you ever must deploy the same application to another environment, you can use these archived files.

See Also:

Oracle Database Utilities for information about Oracle Data Pump, which enables very high-speed movement of data and metadata from one database to another

Index

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W

Symbols

%FOUND cursor attribute, 7.9.4

%ISOPEN cursor attribute, 7.9.4

%NOTFOUND cursor attribute, 7.9.4

%ROWCOUNT cursor attribute, 7.9.4

%ROWTYPE attribute, 7.9.1

%TYPE attribute

in CALCULATE_SCORE function, 7.7.3

purpose of, 7.7.2

A

accent-insensitive sort, 9.5.12

accessing Oracle Database, 1.3.2

See also connecting to Oracle Database

Add Check tool, 6.3.3.2

Add Foreign Key tool, 6.3.3.2

Add Primary Key tool, 6.3.3.2

Add Unique tool, 6.3.3.2

ADD_EVALUATION procedure, 7.5.2

AFTER trigger

statement-level example, 8.2.2

system example, 8.2.5

what it is, 8.1

aggregate conversion function in query, 4.10.7

alias

for column, 4.5

for table, 4.9

See also synonym

ALTER FUNCTION statement, 7.5.4

ALTER PROCEDURE statement, 7.5.4

ALTER TABLE statement

adding constraint with

Foreign Key, 6.3.3.2

Not Null, 6.3.3.2

Primary Key, 6.3.3.2

changing trigger status with, 8.4

ALTER TRIGGER statement

changing trigger status with, 8.4

recompiling trigger with, 8.5

anonymous block, 7.1

APEX (Oracle Application Express), 1.3.2.5.1

application program interface (API), 7.6.1, 7.6.1

archiving installation script file, 10.6

arithmetic operator in query, 4.10.1

array

associative

See associative array

variable, 7.10.1

ASP.NET, 1.3.2.5.9

assignment operator &(colon;=)

assigning initial value to constant with, 7.7

assigning value to associative array element with, 7.10.2

assigning value to variable with, 7.7.4.1

See also SELECT INTO statement

associative array

declaring, 7.10.3

dense, 7.10.2

indexed by integer, 7.10.2

indexed by string, 7.10.2

populating, 7.10.4

sparse, 7.10.2

traversing

dense, 7.10.5

sparse, 7.10.6

what it is, 7.10.2

attribute

%ROWTYPE, 7.9.1

%TYPE, 7.7.2

cursor

See cursor attribute

B

base type, 7.4

basic LOOP statement, 7.8.6

BEFORE trigger

row-level example, 8.2.3

system example, 8.2.5

what it is, 8.1

block

anonymous, 7.1

parts of, 1.3.2.4

body of subprogram, 7.5.1

browsing HR sample schema, 3.1

built-in data type, 6.3.1

BULK COLLECT INTO clause, 7.10.4

byte semantics, 9.1.7

C

C numeric format element, 9.5.10

calculate_score function

creating, 7.5.3

testing, 7.5.5

calendar format, 9.1.4

CASE expression in query, 4.10.9

case sensitivity

in PL/SQL identifiers, 7.3

in sort, 9.5.12

CASE statement, 4.10.9, 7.8.3

character function in query, 4.10.4

character semantics, 9.1.7

character set

conversion and data loss, 9.6.2

length semantics and, 9.1.7

Check Constraint

adding with Add Check tool, 6.3.3.2

what it is, 6.3.3.1

checking validity of installation, 10.5

CLR (Common Language Runtime), 1.3.2.5.9

collapsing displayed information in SQL Developer, 3.1

collating sequence, 9.1.6

collection, 7.10.1

collection method

COUNT, 7.10.5

FIRST, 7.10.6

invoking, 7.10.1

NEXT, 7.10.6

what it is, 7.10.1

column

alias for, 4.5

new heading for, 4.5

qualifying name of, 4.9

relationship to field, 1.3.1

selecting specific one in table, 4.4

comment in PL/SQL code, 7.5.1

Commit Changes icon, 5.3

COMMIT statement

explicit, 5.3

implicit, 5.3

committing transaction

explicitly, 5.3

implicitly, 5.3

Common Language Runtime (CLR), 1.3.2.5.9

composite variable

collection, 7.10.1

record, 7.9.1

compound trigger, 8.1

concatenation operator in query, 4.10.3

conditional predicate, 8.2.2

conditional selection statement

CASE, 7.8.3

IF, 7.8.2

what it is, 7.8.1

connecting to Oracle Database

as user HR, 2.3

from SQL Developer, 2.2

from SQL*Plus, 2.1

constant

declaring, 7.7.1

ensuring correct data type of, 7.7.2

in package body, 7.7

in package specification, 7.7

local, 7.7

what it is, 7.7

constraint

adding to table

with ALTER TABLE statement, 6.3.3.2

with Edit Table tool, 6.3.3.2

application deployment and, 10.2.2

enabled or disabled, 6.3.3

types of, 6.3.3.1

viewing, 3.2

what it is, 6.3.3

controlling program flow, 7.8

conversion function in query, 4.10.6

COUNT collection method, 7.10.5

Create Body tool, 7.6.4

Create Database Synonym tool, 6.6.1

CREATE FUNCTION statement, 7.5.3

CREATE INDEX statement

changing index with, 6.3.7.2

creating index with, 6.3.7.1

Create Index tool, 6.3.7.1

CREATE PACKAGE BODY statement, 7.6.4

CREATE PACKAGE statement

changing package specification with, 7.6.3

creating package specification with, 7.6.2

Create PL/SQL Function tool, 7.5.3

Create PL/SQL Package tool, 7.6.2

Create PL/SQL Procedure tool, 7.5.2

CREATE PROCEDURE statement, 7.5.2

CREATE SEQUENCE statement

in general, 6.5.1

in installation script, 10.3.2

Create Sequence tool, 6.5.1

CREATE SYNONYM statement, 6.6.1

CREATE TABLE statement, 6.3.2.2

Create Table tool, 6.3.2.1

CREATE TRIGGER statement

changing trigger with, 8.3

creating trigger with, 8.2

Create Trigger tool, 8.2

CREATE VIEW statement

changing view with, 6.4.2

creating view with, 6.4.1.2

Create View tool, 6.4.1.1

creation script

See installation script

CURRVAL pseudocolumn, 6.5

cursor

declaring associative array with, 7.10.3

explicit, 7.9.4

implicit, 7.9.4

populating associative array with, 7.10.4

what it is, 7.9.4

cursor attribute

%FOUND, 7.9.4

%ISOPEN, 7.9.4

%NOTFOUND, 7.9.4

%ROWCOUNT, 7.9.4

possible values of, 7.9.4

syntax for value of, 7.9.4

what it is, 7.9.4

cursor type

cursor variable

retrieving result set rows one at a time with

procedure, 7.9.8

tutorial, 7.9.9

what it is, 7.9.7

D

data definition language statement

See DDL statement

data integrity

See constraint

data loss during character-set conversion, 9.6.2

data manipulation language statement

See DML statement

Data pane, 6.3.5

data type

base, 7.4

built-in, 6.3.1

of associative array key, 7.10.2

of constant, 7.4

of function return value, 7.4

of subprogram parameter, 7.4

of table column, 6.3.1

of variable, 7.4

PL/SQL, 7.4

SQL, 6.3.1

SQL national character, 9.1.8

subtype of, 7.4

Unicode, 9.1.8

user-defined, 6.3.1

Database Export tool, 10.3.1

database initialization parameter, 9.2

date format, 9.1.3

datetime format model, 4.10.6

datetime function in query, 4.10.5

DBMS_OUTPUT.PUT_LINE procedure, 7.8.3

DBMS_STANDARD.RAISE_APPLICATION_ERROR procedure, 7.11.1

DDL statement

as triggering event, 8.1

in installation script file, 10.2

what it is, 6.1

decimal character, 9.5.8

declarative language, 1.3.2.3

declarative part

of block, 1.3.2.4

of subprogram, 7.5.1

DECODE function in query, 4.10.10

Delete Selected Row(s) tool, 6.3.6

DELETE statement, 5.1.3

DELETING conditional predicate, 8.2.2

deleting entire table, 6.3.8

deleting row from table

with Delete Selected Row(s) tool, 6.3.6

with DELETE statement, 5.1.3

dense associative array

populating, 7.10.4

traversing, 7.10.5

what it is, 7.10.2

dependencies between schema objects

installation and, 10.2.1

trigger compilation and, 8.5

deploying application, 10.1

deployment environment, 10.1

development environment

choice of, 1.3.2.5

for sample application, 2.3

what it is, 10.1

disabled trigger, 8.1

disabling triggers

in general, 8.4

all triggers in table, 8.4

in installation script, 10.3.3

DISTINCT option, 4.10.7

DL (long date) format, 9.5.4

DML statement

as triggering event, 8.1

associative arrays and, 7.10.2

implicit cursor for, 7.9.4

what it is, 5.1

dot notation

for accessing record field, 7.9.1

for invoking collection method, 7.10.1

DROP FUNCTION statement, 7.5.6

DROP INDEX statement, 6.3.7.2, 6.3.7.3

DROP PACKAGE statement, 7.6.5

DROP PROCEDURE statement, 7.5.6

DROP SEQUENCE statement, 6.5.2

DROP SYNONYM statement, 6.6.2

DROP TABLE statement, 6.3.8

Drop tool

for index, 6.3.7.3

for package, 7.6.5

for sequence, 6.5.2

for synonym, 6.6.2, 7.5.6

for table, 6.3.8

for trigger, 8.6

for view, 6.4.3

DROP TRIGGER statement, 8.6

DROP VIEW statement, 6.4.3

DS (short date) format, 9.5.4

DUAL table, 4.10.5

E

Edit Index tool, 6.3.7.2

Edit Table tool, 6.3.3.2

Edit tool

changing standalone stored subprogram with, 7.5.4

changing trigger with, 8.3

Edit View tool, 6.4.2

education environment, 10.1

EMP_EVAL package

changing specification for, 7.6.3

creating body of, 7.6.4

creating specification for, 7.6.2

EMP_LOCATIONS view

creating, 6.4.1.2

description of, 6.4.1

enabled trigger, 8.1

enabling triggers

in general, 8.4

all triggers in table, 8.4

in installation script, 10.3.3

ending transaction

by committing, 5.3

by rolling back, 5.4

ensuring data integrity, 6.3.3

environment variables, 9.4

error

See exception

EVALUATIONS table

adding constraint to

Foreign Key, 6.3.3.2

Primary Key, 6.3.3.2

adding index to, 6.3.7.1

creating, 6.3.2.2

creating sequence for, 6.5.1

description of, 6.3.2

EVALUATIONS_SEQ sequence

creating, 6.5.1

using, 8.2.3

exception handler syntax, 7.11.1

exception handling

in general, 7.11.1

for predefined exception, 7.11.2

EXCEPTION_INIT pragma, 7.11.1

exception-handling part

of block, 1.3.2.4

of subprogram, 7.5.1

executable part

of block, 1.3.2.4

of subprogram, 7.5.1

EXIT WHEN statement, 7.8.6

expanding displayed information in SQL Developer, 3.1

explicit cursor

retrieving result set rows one at a time with, 7.9.5

what it is, 7.9.4

exploring Oracle Database, 3

exporting schema objects, 10.3.1

expression in query, 4.10

F

FCL (Framework Class Libraries), 1.3.2.5.9

FETCH statement

explicit cursor and, 7.9.4

populating dense associative array with, 7.10.4

fetching results one row at a time, 7.9.4

field

relationship to column, 1.3.1

what it is, 7.9.1

FIRST collection method, 7.10.6

FOR LOOP statement, 7.8.4

Foreign Key constraint

adding

with Add Foreign Key tool, 6.3.3.2

with ALTER TABLE statement, 6.3.3.2

what it is, 6.3.3.1

format

calendar, 9.1.4

date, 9.1.3

datetime model, 4.10.6

monetary, 9.1.5

time, 9.1.3

Framework Class Libraries (FCL), 1.3.2.5.9

function

in query, 4.10

locale-dependent SQL, 9.4.2

statistical, 4.10.7

structure of, 7.5.1

what it is, 7.1

See also subprogram

G

G numeric format element, 9.5.8

globalization support features, 9.1

See also NLS parameters

group separator in number, 9.5.8

grouping query results, 4.10.7

H

HR sample schema

browsing, 3.1

unlocking, 2.3.1

what it is, 1.4

Hypertext Preprocessor (PHP), 1.3.2.5.3

I

icon names and keyboard equivalents, 1.3.2.2

identifier, 7.3

IF statement, 7.8.2

implicit COMMIT statement, 5.3

implicit cursor, 7.9.4

index

adding, 6.3.7.1

changing, 6.3.7.2

dropping, 6.3.7.3

implicitly created, 6.3.7

what it is, 1.3.1

index-by table

See associative array

initial value of constant or variable, 7.7

initialization parameter, 9.2

Insert Row tool, 6.3.4

INSERT statement

in general, 5.1.1

in installation script file, 10.2

INSERTING conditional predicate, 8.2.2

installation script

disabling and re-enabling triggers in, 10.3.3

editing CREATE SEQUENCE statement in, 10.3.2

what it is, 10.2

installation script file

archiving, 10.6

creating

in general, 10.3

for sample application data, 10.3.7

for sample application package, 10.3.5

for sample application sequence and tables, 10.3.4

for sample application synonym and view, 10.3.6

running, 10.4

what it is, 10.2

INSTEAD OF trigger

example, 8.2.4

what it is, 8.1

integrity constraint

See constraint

intersecting tables, 4.9

invalidated trigger, 8.5

IW date format element, 9.1.4

J

JDBC (Oracle Java Database Connectivity), 1.3.2.5.2

joining tables, 4.9

K

keyboard equivalents of icons, 1.3.2.2

key-value pair

See associative array

L

L numeric format element, 9.5.9

language support, 9.1.1

length semantics, 9.1.7

linguistic sorting and string searching, 9.1.6

local constant, 7.7

local subprogram

in anonymous block, 7.1

in another subprogram, 7.1

in package, 7.6.1

local variable, 7.7

locale, 9.5.1

locale-dependent SQL function, 9.4.2

logical table

See view

long date (DL) format, 9.5.4

loop statement

basic LOOP, 7.8.6

exiting early, 7.8.6

FOR LOOP, 7.8.4

populating associative array with, 7.10.4

what it is, 7.8.1

WHILE LOOP, 7.8.5

M

method, 7.10.1

Microsoft .NET Framework, 1.3.2.5.9

Microsoft Visual Studio, 1.3.2.5.9

monetary format, 9.1.5

multiline comment in PL/SQL code, 7.5.1

multilingual applications, 9.1

N

naming convention

for PL/SQL identifiers, 7.3

for sequences, 6.5

national character set, 9.1.8

National Language Support (NLS), 9.1

National Language Support (NLS) parameters

See NLS parameters

native language support, 9.1.1

NCHAR literal replacement, 9.6.2

nested subprogram

See local subprogram

nested table, 7.10.1

.NET assembly, 1.3.2.5.9

.NET stored procedure, 1.3.2.5.9

NEW pseudorecord, 8.2.1

NEXT collection method, 7.10.6

NEXTVAL pseudocolumn, 6.5

NLS (National Language Support), 9.1

NLS environment variables, 9.4

NLS parameters

of locale-dependent SQL functions, 9.4.2

values of

changing, 9.4

initial, 9.2

viewing, 9.3

what they are, 9.1

NLS_CALENDAR parameter, 9.5.7

NLS_COMP parameter, 9.5.13

NLS_CURRENCY parameter, 9.5.9

NLS_DATE_FORMAT parameter, 9.5.4

NLS_DATE_LANGUAGE parameter, 9.5.5

NLS_DUAL_CURRENCY parameter, 9.5.11

NLS_ISO_CURRENCY parameter, 9.5.10

NLS_LANG parameter, 9.5.1

NLS_LANGUAGE parameter, 9.5.2

NLS_LENGTH_SEMANTICS parameter, 9.5.14

NLS_NUMERIC_CHARACTERS parameter, 9.5.8

NLS_SORT parameter, 9.5.12

NLS_TERRITORY parameter, 9.5.3

NLS_TIMESTAMP_FORMAT parameter, 9.5.6

nonprocedural language, 1.3.2.3

Not Null constraint

adding

with ALTER TABLE statement, 6.3.3.2

with Edit Table tool, 6.3.3.2

what it is, 6.3.3.1

numeric format

elements

C, 9.5.10

G, 9.5.8

L, 9.5.9

in different countries, 9.1.5

numeric function in query, 4.10.2

NVL function, 4.10.8

NVL2 function, 4.10.8

O

objects

See schema object

OCCI (Oracle C++ Call Interface), 1.3.2.5.5

OCI (Oracle Call Interface), 1.3.2.5.4

ODBC (Open Database Connectivity), 1.3.2.5.6

ODP.NET, 1.3.2.5.9

ODT (Oracle Developer Tools for Visual Studio), 1.3.2.5.9

OLD pseudorecord, 8.2.1

OO4O (Oracle Objects for OLE), 1.3.2.5.11

Open Database Connectivity (ODBC), 1.3.2.5.6

OR REPLACE clause in DDL statement, 6.1

Oracle Application Express (APEX), 1.3.2.5.1

Oracle C++ Call Interface (OCCI), 1.3.2.5.5

Oracle Call Interface (OCI), 1.3.2.5.4

Oracle Database Extensions for .NET, 1.3.2.5.9

Oracle Deployment Wizard for .NET, 1.3.2.5.9

Oracle Developer Tools for Visual Studio, 1.3.2.5.9

Oracle Java Database Connectivity (JDBC), 1.3.2.5.2

Oracle Objects for OLE (OO4O), 1.3.2.5.11

Oracle Provider for OLE DB (OraOLEDB), 1.3.2.5.10

Oracle Providers for ASP.NET, 1.3.2.5.9

OraOLEDB (Oracle Provider for OLE DB), 1.3.2.5.10

ORDER BY clause of SELECT statement, 4.8

P

package

dropping, 7.6.5

reasons to use, 7.2

structure of, 7.6.1

what it is, 7.2

package body

changing, 7.7.1

creating, 7.6.4

what it is, 7.6.1

package specification

changing, 7.6.3

creating, 7.6.2

what it is, 7.6.1

package subprogram, 7.1

parameter

See subprogram parameter

pattern (regular expression), 4.7

PERCENT_RANK function, 4.10.7

PERFORMANCE_PARTS table

adding constraint to

Not Null, 6.3.3.2, 6.3.3.2

Primary Key, 6.3.3.2

adding rows to, 6.3.4

changing data in, 6.3.5

creating, 6.3.2.1

deleting data from, 6.3.6

description of, 6.3.2

PHP (Hypertext Preprocessor), 1.3.2.5.3

PLS_INTEGER data type, 7.4

PL/SQL block

anonymous, 7.1

parts of, 1.3.2.4

PL/SQL data type, 7.4

PL/SQL identifier, 7.3

PL/SQL language, 1.3.2.4

PL/SQL table

See associative array

PL/SQL unit, 1.3.2.4

precompiler

Pro*C/C++, 1.3.2.5.7

Pro*COBOL, 1.3.2.5.8

predefined exception

handling, 7.11.2

what it is, 7.11.1

Primary Key constraint

adding

with Add Primary Key tool, 6.3.3.2

with ALTER TABLE statement, 6.3.3.2

what it is, 6.3.3.1

private SQL area, 7.9.4

Pro*C/C++ precompiler, 1.3.2.5.7

Pro*COBOL precompiler, 1.3.2.5.8

Procedural Language/SQL (PL/SQL) language, 1.3.2.4

procedure

structure of, 7.5.1

what it is, 7.1

See also subprogram

production environment, 10.1

program flow control, 7.8

pseudorecord, 8.2.1

Q

qualifying column names, 4.9

query

function in, 4.10

grouping results by column, 4.10.7

improving readability of, 4.9

operator in, 4.10

simple, 4.1

SQL expression in, 4.10

stored

See view

what it is, 4.1

R

RAISE statement, 7.11.1

RAISE_APPLICATION_ERROR procedure, 7.11.1

RANK function, 4.10.7

record

creating, 7.9.1

creating type for, 7.9.2

relationship to row, 1.3.1

what it is, 7.9.1

reducing disk I/O, 6.3.7

REF constraint, 6.3.3.1

REF CURSOR type, 7.9.7

REF CURSOR variable

See cursor variable

Refresh icon

DDL statements and, 6.1

DML statements and, 5.1

rolling back transactions and, 5.4

REGEXP_COUNT function, 4.7

REGEXP_LIKE function, 4.7, 4.7

REGEXP_REPLACE function, 4.7

regular expression in query, 4.7

RENAME statement, 6.4.2

Rename tool, 6.4.2

resetting password of HR account, 2.3.1

retrieving results one row at a time, 7.9.4

RETURN clause of function, 7.5.1

RETURN statement, 7.5.1

return type

of cursor variable, 7.9.7

of function, 7.4

of REF CURSOR type, 7.9.7

reversing transaction, 5.4

Rollback Changes icon, 5.4

ROLLBACK statement, 5.4

rolling back transaction, 5.4

row

adding

with Insert Row tool, 6.3.4

with INSERT statement, 5.1.1

relationship to record, 1.3.1

row-level trigger

example, 8.2.3

pseudorecords and, 8.2.1

what it is, 8.1

Run tool, 7.5.5

running installation script file, 10.4

run-time error

See exception

S

SAL_INFO RECORD type

creating, 7.9.2

creating parameter of, 7.9.3

SALARY_SCHEDULE procedure

creating, 7.9.3

invoking, 7.9.3

SALESFORCE view

changing, 6.4.2

creating, 6.4.1.1

description of, 6.4.1

sample application

creating API for, 7.6.2

creating package body for, 7.6.4

creating package specification for, 7.6.2

creating sequence for, 6.5.1

creating synonym for, 6.6.1

creating tables for, 6.3.2

creating triggers for

INSTEAD OF trigger, 8.2.4

row-level BEFORE trigger, 8.2.3

statement-level AFTER trigger, 8.2.2

creating views for, 6.4.1

development environment for, 2.3

installing (deploying), 10.4

sample schema HR

See HR sample schema, 1.4

SAVEPOINT statement, 5.5

schema, 1.3

schema object

dependent

installation and, 10.2.1

trigger compilation and, 8.5

exporting, 10.3.1

viewing, 3.1

what it is, 1.3

schema-level subprogram

See standalone stored subprogram

SCORES table

adding constraint to

Check, 6.3.3.2

Foreign Key, 6.3.3.2

Unique, 6.3.3.2

creating, 6.3.2.2

description of, 6.3.2

script

See installation script

searched CASE statement, 7.8.3

SELECT INTO statement

assigning value to variable with, 7.7.4.2

associative array and, 7.10.2

implicit cursor for, 7.9.4

See also assignment operator &(colon;=)

SELECT statement

ORDER BY clause of, 4.8

simple, 4.1

WHERE clause of, 4.6

selecting table data

in general, 4.1

and sorting it, 4.8

that matches regular expression, 4.7

that matches specified conditions, 4.6

semantics

byte, 9.1.7

character, 9.1.7

length, 9.1.7

sequence

creating, 6.5.1

dropping, 6.5.2

in installation script, 10.3.2

what it is, 6.5

sequential control statement, 7.8.1

setting savepoints in transaction, 5.5

short date (DS) format, 9.5.4

signature of subprogram, 7.5.1

simple CASE statement, 7.8.3

simple trigger, 8.1

single-line comment in PL/SQL code, 7.5.1

sorting

accent-insensitive, 9.5.12

case-insensitive, 9.5.12

linguistic, 9.1.6

selected data, 4.8

source and new tables, 10.2

sparse associative array

populating, 7.10.4

traversing, 7.10.6

what it is, 7.10.2

SQL cursor (implicit cursor), 7.9.4

SQL data type, 6.3.1

SQL Developer

collapsing displayed information in, 3.1

connecting to Oracle Database from

in general, 2.2

as user HR, 2.3.3

expanding displayed information in, 3.1

exploring database with, 3

icon names and keyboard equivalents in, 1.3.2.2

initial values of NLS parameters in, 9.2

what it is, 1.3.2.2

SQL expression in query, 4.10

SQL language, 1.3.2.3

SQL national data types, 9.1.8

SQL pane, 6.3.2.2

SQL*Plus

connecting to Oracle Database from

in general, 2.1

as user HR, 2.3.2

what it is, 1.3.2.1

standalone stored subprogram

changing, 7.5.4

creating

function, 7.5.3

procedure, 7.5.2

dropping, 7.5.6

what it is, 7.1

statement-level trigger

example, 8.2.2

what it is, 8.1

statistical function, 4.10.7

stored query

See view

stored subprogram, 7.1

strong REF CURSOR type, 7.9.7

strongly typed cursor variable, 7.9.7, 7.9.7

struct type

See record

Structured Query Language (SQL), 1.3.2.3

subprogram

body of, 7.5.1

local

See local subprogram

nested

See local subprogram

package, 7.1

parameter of

See subprogram parameter

parts of, 7.5.1

schema-level

See standalone stored subprogram

signature of, 7.5.1

standalone stored

See standalone stored subprogram

stored, 7.1

structure of, 7.5.1

what it is, 7.1

subprogram parameter

collection as, 7.10.1

cursor variable as, 7.9.7

ensuring correct data type of, 7.7.2

for standalone subprogram, 7.2

record as, 7.9.1

subquery, 4.1

subscript notation, 7.10.1

subtype, 7.4

synonym

creating, 6.6.1

dropping, 6.6.2

what it is, 6.6

See also alias

SYS_REFCURSOR predefined type, 7.9.7

system trigger

example, 8.2.5

what it is, 8.1

SYSTIMESTAMP function, 4.10.5

T

table

adding constraint to

with ALTER TABLE statement, 6.3.3.2

with Edit Table tool, 6.3.3.2

adding row to

with Insert Row tool, 6.3.4

with INSERT statement, 5.1.1

alias for, 4.9

changing data in

in Data pane, 6.3.5

with UPDATE statement, 5.1.2

creating, 6.3.2

deleting row from

with Delete Selected Row(s) tool, 6.3.6

with DELETE statement, 5.1.3

dropping, 6.3.8

ensuring data integrity in, 6.3.3

index on

See index

logical

See view

selecting data from

in general, 4.1

and sorting it, 4.8

that matches regular expression, 4.7

that matches specified conditions, 4.6

selecting specific columns of, 4.4

source and new, 10.2

viewing data in, 3.2

viewing properties of, 3.2

virtual

See view

what it is, 6.3

territory support, 9.1.2

test environment, 10.1

time format, 9.1.3

timing point of trigger, 8.1

trace file, 7

transaction, 5.2

committing

explicitly, 5.3

implicitly, 5.3

ending

by committing, 5.3

by rolling back, 5.4

rolling back, 5.4

setting savepoints in, 5.5

visibility of, 5.3

transaction control statements, 5.2

trigger

AFTER

statement-level example, 8.2.2

system example, 8.2.5

what it is, 8.1

BEFORE

row-level example, 8.2.3

system example, 8.2.5

what it is, 8.1

changing, 8.3

compiling, 8.5

compound, 8.1

creating, 8.2

disabled, 8.1

disabling

in general, 8.4

in installation script, 10.3.3

dropping, 8.6

enabled, 8.1

enabling

in general, 8.4

in installation script, 10.3.3

INSTEAD OF

example, 8.2.4

what it is, 8.1

invalidated, 8.5

on view, 8.2.4

recompiling, 8.5

row-level

example, 8.2.3

pseudorecords and, 8.2.1

what it is, 8.1

simple, 8.1

statement-level

example, 8.2.2

what it is, 8.1

system

example, 8.2.5

what it is, 8.1

timing point of, 8.1

what it is, 1.3.1, 8.1

U

undoing transaction, 5.4

Unicode

data types for, 9.1.8

string literals in, 9.6.1

what it is, 9.1.8

Unique constraint

adding with Add Unique tool, 6.3.3.2

what it is, 6.3.3.1

unlocking HR account, 2.3.1

UPDATE statement, 5.1.2

UPDATING conditional predicate, 8.2.2

user-defined data type, 6.3.1

user-defined exception, 7.11.1

V

validity of installation, 10.5

variable

assigning value to

with assignment operator, 7.7.4.1

with SELECT INTO statement, 7.7.4.2

composite

collection, 7.10.1

record, 7.9.1

cursor

See cursor variable

declaring, 7.7.1

ensuring correct data type of, 7.7.2

in package body, 7.7

in package specification, 7.7

local, 7.7

what it is, 7.7

variable array (varray), 7.10.1

view

changing, 6.4.2

creating, 6.4.1

dropping, 6.4.3

trigger on, 8.2.4

what it is, 6.4

viewing schema object, 3.1

viewing table data, 3.2

viewing table properties, 3.2

virtual table

See view

visibility of transaction, 5.3

Visual Studio, 1.3.2.5.9

W

weak REF CURSOR type, 7.9.7

WHEN OTHERS exception handler, 7.11.1

WHERE clause of SELECT statement, 4.6

WHILE LOOP statement, 7.8.5

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