|Programmer's Guide to the Oracle Precompilers, 1.8||
An important feature of this guide is its emphasis on getting the most out of the Oracle Precompilers and embedded SQL. To help you master these tools, this guide shows you all the "tricks of the trade" including ways to improve program performance. It also includes many program examples to better your understanding and demonstrate the usefulness of embedded SQL.
Note: You will not find installation instructions or system-specific information in this guide. For information about migrating your applications from Oracle Version 6 to Oracle7, see Appendix E.
To use this guide effectively, you need a working knowledge of the following subjects:
For more information, see Appendix A.
Chapter 1: Getting Acquainted This chapter introduces you to the Oracle Precompilers. You look at their role in developing application programs that manipulate Oracle data and find out what they allow your applications to do.
Chapter 2: Learning the Basics This chapter explains how embedded SQL programs do their work. You examine the special environment in which they operate, the impact of this environment on the design of your applications, the key concepts of embedded SQL programming, and the steps you take in developing an application.
Chapter 3: Meeting Program Requirements This chapter shows you how to meet embedded SQL program requirements. You learn the embedded SQL commands that declare variables, declare communications areas, and connect to an Oracle database. You also learn about the Oracle datatypes, National Language Support (NLS), data conversion, and how to take advantage of datatype equivalencing. In addition, this chapter shows you how to embed Oracle Call Interface (OCI) calls in your program and how to develop X/Open applications.
Chapter 4: Using Embedded SQL This chapter teaches you the essentials of embedded SQL programming. You learn how to use host variables, indicator variables, cursors, cursor variables, and the fundamental SQL commands that insert, update, select, and delete Oracle data.
Chapter 5: Using Embedded PL/SQL This chapter shows you how to improve performance by embedding PL/SQL transaction processing blocks in your program. You learn how to use PL/SQL with host variables, indicator variables, cursors, stored subprograms, host arrays, and dynamic SQL.
Chapter 6: Running the Oracle Precompilers This chapter details the requirements for running an Oracle Precompiler. You learn what happens during precompilation, how to issue the precompiler command, how to specify the many useful precompiler options, how to do conditional and separate precompilations, and how to embed OCI calls in your host program.
Chapter 7: Defining and Controlling Transactions This chapter describes transaction processing. You learn the basic techniques that safeguard the consistency of your database.
Chapter 8: Handling Runtime Errors This chapter provides an in-depth discussion of error reporting and recovery. You learn how to detect and handle errors using the status variable SQLSTATE, the SQLCA structure, and the WHENEVER statement. You also learn how to diagnose problems using the ORACA.
Chapter 9: Using Host Arrays This chapter looks at using arrays to improve program performance. You learn how to manipulate Oracle data using arrays, how to operate on all the elements of an array with a single SQL statement, and how to limit the number of array elements processed.
Chapter 10: Using Dynamic SQL This chapter shows you how to take advantage of dynamic SQL. You are taught four methods--from simple to complex--for writing flexible programs that, among other things, let users build SQL statements interactively at run time.
Chapter 11: Writing User Exits This chapter focuses on writing user exits for your SQL*Forms or Oracle Forms applications. First, you learn the commands that allow a Forms application to interface with user exits. Then, you learn how to write and link a Forms user exit.
Appendix A: New Features This appendix highlights the improvements and new features introduced with Release 1.8 of the Oracle Precompilers.
Appendix B: Oracle Reserved Words, Keywords, and Namespaces This appendix lists words that have a special meaning to Oracle and namespaces that are reserved for Oracle libraries.
Appendix C: Performance Tuning This appendix gives you some simple, easy-to-apply methods for improving the performance of your applications.
Appendix D: Syntactic and Semantic Checking This appendix shows you how to use the SQLCHECK option to control the type and extent of syntactic and semantic checking done on embedded SQL statements and PL/SQL blocks.
Appendix E: Migrating to Oracle7 Oracle7 conforms fully to the new ANSI/ISO SQL standard. As a result, Oracle7 and Oracle Version 6 behave differently in a few areas. By pointing out those areas, this appendix helps you migrate your application programs to Oracle7.
Appendix F: Embedded SQL Commands and Directives This appendix contains descriptions of precompiler directives, embedded SQL commands, and Oracle embedded SQL extensions. These commands are prefaced in your source code with the keywords, EXEC SQL.
With a few exceptions, program examples are written in pseudocode to avoid language-specific issues. Oriented to professional programmers, the pseudocode is somewhat formal. In the following example, a mail order for books is processed:
-- process book order IF prepaid OR (credit_rating > 2) THEN set order_total = 0; -- initialize order_total FOR EACH book IF catalog_number is valid THEN EXEC SQL SELECT QTY INTO :quantity_on_hand FROM STOCK WHERE CATNO = :catalog_number; IF quantity_on_hand > 0 THEN set line_price = catalog_price; set line_total = line_price * quantity; add line_total to order_total; subtract quantity from quantity_on_hand; create order_line; ELSE create back_order; ENDIF; ELSE display 'Invalid catalog number'; ENDIF; ENDFOR; create customer_order; ELSE display 'Credit rating too low'; ENDIF;
This example has the following important features:
Angle brackets enclose the name of a syntactic element.
A dot separates an object name from a component name and so qualifies a reference.
Two dots separate the lowest and highest values in a range.
. . .
An ellipsis shows that statements or clauses irrelevant to the discussion were left out.
This character is used in text to represent blank spaces when referring to the content of a database column.
Brackets enclose optional items.
Braces enclose items only one of which is required.
A vertical bar separates alternatives within brackets or braces.
. . .
An ellipsis shows that the preceding parameter can be repeated.
ANSI standard X3.135-1992 (known informally as SQL92) provides three levels of compliance:
A conforming SQL implementation must support at least Entry SQL. The Oracle Pro*COBOL and Pro*FORTRAN Precompilers do conform to Entry SQL92.
NIST standard FIPS PUB 127-1, which applies to RDBMS software acquired for federal use, also adopts the ANSI standards. In addition, it specifies minimum sizing parameters for database constructs and requires a "FIPS Flagger" to identify ANSI extensions.
For copies of the ANSI standards, write to
American National Standards Institute
New York, NY 10018
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