Preface

This reference contains a complete description of the Structured Query Language (SQL) used to manage information in an Oracle database. Oracle SQL is a superset of the American National Standards Institute (ANSI) and the International Standards Organization (ISO) SQL99 standard.

This preface contains these topics:

Audience

The SQL Reference is intended for all users of Oracle SQL.

Organization

This reference is divided into the following parts:

Chapter 1, "Introduction"

This chapter discusses the history of SQL and describes the advantages of using it to access relational databases.

Chapter 2, "Basic Elements of Oracle SQL"

This chapter describes the basic building blocks of an Oracle database and of Oracle SQL.

Chapter 3, "Operators"

This chapter describes SQL operators.

Chapter 4, "Expressions"

This chapter describes SQL expressions.

Chapter 5, "Conditions"

This chapter describes SQL conditions.

Chapter 6, "Functions"

This chapter describes how to use SQL functions.

Chapter 7, "SQL Queries and Other SQL Statements"

This chapter describes the different types of SQL queries and lists the various types of SQL statements.

Chapter 8, "SQL Statements: ALTER CLUSTER to ALTER SEQUENCE"

Chapter 9, "SQL Statements: ALTER SESSION to ALTER SYSTEM"

Chapter 10, "SQL Statements: ALTER TABLE to ALTER TABLESPACE"

Chapter 11, "SQL Statements: ALTER TRIGGER to constraint_clause"

Chapter 12, "SQL Statements: CREATE CLUSTER to CREATE JAVA"

Chapter 13, "SQL Statements: CREATE LIBRARY to CREATE SPFILE"

Chapter 14, "SQL Statements: CREATE SYNONYM to CREATE TRIGGER"

Chapter 15, "SQL Statements: CREATE TYPE to DROP ROLLBACK SEGMENT"

Chapter 16, "SQL Statements: DROP SEQUENCE to ROLLBACK"

Chapter 17, "SQL Statements: SAVEPOINT to UPDATE"

These chapters list and describe all Oracle SQL statements in alphabetical order.

Appendix A, "How to Read Syntax Diagrams"

This appendix describes how to read the syntax diagrams in this reference.

Appendix B, "Oracle and Standard SQL"

This appendix describes Oracle compliance with ANSI and ISO standards.

Appendix C, "Oracle Reserved Words"

This appendix lists words that are reserved for internal use by Oracle.

Structural Changes in the SQL Reference in Oracle9i Release 1 (9.0.1)

The chapter that formerly described expressions, conditions, and queries has been divided. Conditions and expressions are now two separate chapters, and queries are described in Chapter 7, "SQL Queries and Other SQL Statements".

CAST, DECODE, and EXTRACT (datetime), which were formerly documented as forms of expression, are now documented as SQL built-in functions.

LIKE and the elements formerly called "comparison operators" and "logical operators" are now documented as SQL conditions.

The chapters containing all SQL statements (formerly Chapters 7 through 10) has been divided into ten chapters for printing purposes.

Structural Changes in the SQL Reference in Oracle8i

Users familiar with the Release 8.0 documentation will find that the following sections have been moved or renamed:

The section "Format Models" now appears in Chapter 2.
Chapter 3 has been divided into several smaller chapters:
- Chapter 3, "Operators"
- Chapter 6, "Functions"
- Chapter 4, "Expressions". The last section, "Queries and Subqueries", provides background for the syntactic and semantic information in SELECT .
A new chapter, Chapter 8, "About SQL Statements", has been added to help you find the correct SQL statement for a particular task.
The archive_log_clause is no longer a separate section, but has been incorporated into ALTER SYSTEM .
The deallocate_unused_clause is no longer a separate section, but has been incorporated into ALTER TABLE , ALTER CLUSTER , and ALTER INDEX .
The disable_clause is no longer a separate section, but has been incorporated into CREATE TABLE and ALTER TABLE .
The drop_clause is no longer a separate section. It has become the drop_constraint_clause of the ALTER TABLE statement (to distinguish it from the new drop_column_clause of that statement). See ALTER TABLE .
The enable_clause is no longer a separate section, but has been incorporated into CREATE TABLE and ALTER TABLE .
The parallel_clause is no longer a separate section. The clause has been simplified, and has been incorporated into the various statements where it is relevant.
The recover_clause is no longer a separate section. Recovery functionality has been enhanced, and because it is always implemented through the ALTER DATABASE statement, it has been incorporated into that section. See ALTER DATABASE .
The sections on snapshots and snapshot logs have been moved and renamed. Snapshot functionality has been greatly enhanced, and these objects are now called materialized views. See CREATE MATERIALIZED VIEW , ALTER MATERIALIZED VIEW , DROP MATERIALIZED VIEW , CREATE MATERIALIZED VIEW LOG , ALTER MATERIALIZED VIEW LOG , and DROP MATERIALIZED VIEW LOG .
The section on subqueries has now been combined with the SELECT statement. See SELECT .
The two SQL statements GRANT object_privileges and GRANT system_privileges_and_roles have been combined into one GRANT statement. See GRANT .
The two SQL statements REVOKE schema_object_privileges and REVOKE system_privileges_and_roles have been combined into one REVOKE statement. See REVOKE .
The two SQL statements AUDIT sql_statements and AUDIT schema_objects have been combined into one AUDIT statement. See AUDIT .
The two SQL statements NOAUDIT sql_statements and NOAUDIT schema_objects have been combined into one NOAUDIT statement. See NOAUDIT .

Conventions

This section describes the conventions used in the text and code examples of this documentation set. It describes:

Conventions in Text

We use various conventions in text to help you more quickly identify special terms. The following table describes those conventions and provides examples of their use.

Convention	Meaning	Example
Bold	Bold typeface indicates terms that are defined in the text or terms that appear in a glossary, or both.	When you specify this clause, you create an index-organized table.
Italics	Italic typeface indicates book titles or emphasis.	Oracle9i Database Concepts Ensure that the recovery catalog and target database do not reside on the same disk.
`UPPERCASE monospace (fixed-width font)`	Uppercase monospace typeface indicates elements supplied by the system. Such elements include parameters, privileges, datatypes, RMAN keywords, SQL keywords, SQL*Plus or utility commands, packages and methods, as well as system-supplied column names, database objects and structures, usernames, and roles.	You can specify this clause only for a `NUMBER` column. You can back up the database by using the `BACKUP` command. Query the `TABLE_NAME` column in the `USER_TABLES` data dictionary view. Use the `DBMS_STATS`.`GENERATE_STATS` procedure.
`lowercase monospace (fixed-width font)`	Lowercase monospace typeface indicates executables, filenames, directory names, and sample user-supplied elements. Such elements include computer and database names, net service names, and connect identifiers, as well as user-supplied database objects and structures, column names, packages and classes, usernames and roles, program units, and parameter values. Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.	Enter `sqlplus` to open SQL*Plus. The password is specified in the `orapwd` file. Back up the datafiles and control files in the `/disk1/oracle/dbs` directory. The `department_id`, `department_name`, and `location_id` columns are in the `hr.departments` table. Set the `QUERY_REWRITE_ENABLED` initialization parameter to `true.` Connect as `oe` user. The `JRepUtil` class implements these methods.
`lowercase monospace (fixed-width font) italic`	Lowercase monospace italic font represents placeholders or variables.	You can specify the `parallel_clause`. Run `U``old_release``.SQL` where `old_release` refers to the release you installed prior to upgrading.

Conventions in Code Examples

Code examples illustrate SQL, PL/SQL, SQL*Plus, or other command-line statements. They are displayed in a monospace (fixed-width) font and separated from normal text as shown in this example:

SELECT username FROM dba_users WHERE username = 'MIGRATE';

The following table describes typographic conventions used in code examples and provides examples of their use.

Convention	Meaning	Example
[ ]	Brackets enclose one or more optional items. Do not enter the brackets.	`DECIMAL (``digits` `[ ,` `precision` `])`
{ }	Braces enclose two or more items, one of which is required. Do not enter the braces.	`{ENABLE \| DISABLE}`
\|	A vertical bar represents a choice of two or more options within brackets or braces. Enter one of the options. Do not enter the vertical bar.	`{ENABLE \| DISABLE}` `[COMPRESS \| NOCOMPRESS]`
`...`	Horizontal ellipsis points indicate either: That we have omitted parts of the code that are not directly related to the example That you can repeat a portion of the code	`CREATE TABLE ... AS` `subquery``;` `SELECT` `col1``,` `col2``, ... ,` `coln` `FROM employees;`
. . .	Vertical ellipsis points indicate that we have omitted several lines of code not directly related to the example.
Other notation	You must enter symbols other than brackets, braces, vertical bars, and ellipsis points as shown.	`acctbal NUMBER(11,2);` `acct CONSTANT NUMBER(4) := 3;`
`Italics`	Italicized text indicates placeholders or variables for which you must supply particular values.	`CONNECT SYSTEM/``system_password` `DB_NAME =` `database_name`
`UPPERCASE`	Uppercase typeface indicates elements supplied by the system. We show these terms in uppercase in order to distinguish them from terms you define. Unless terms appear in brackets, enter them in the order and with the spelling shown. However, because these terms are not case sensitive, you can enter them in lowercase.	`SELECT last_name, employee_id FROM employees;` `SELECT * FROM USER_TABLES;` `DROP TABLE hr.employees;`
`lowercase`	Lowercase typeface indicates programmatic elements that you supply. For example, lowercase indicates names of tables, columns, or files. Note: Some programmatic elements use a mixture of UPPERCASE and lowercase. Enter these elements as shown.	`SELECT last_name, employee_id FROM employees;` `sqlplus hr/hr` `CREATE USER mjones IDENTIFIED BY ty3MU9;`

Documentation Accessibility

Oracle's goal is to make our products, services, and supporting documentation accessible to the disabled community with good usability. 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. 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 additional information, visit the Oracle Accessibility Program Web site at

http://www.oracle.com/accessibility/

JAWS, a Windows screen reader, 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, JAWS may not always read a line of text that consists solely of a bracket or brace.