Release 8.1.5
A67842-01
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| PL/SQL User's Guide and Reference Release 8.1.5 A67842-01 |
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PL/SQL, Oracle's procedural extension to SQL, is an advanced fourth-generation programming language (4GL). It offers modern features such as data encapsulation, overloading, collection types, exception handling, and information hiding. PL/SQL also offers seamless SQL access, tight integration with the Oracle server and tools, portability, and security.
This guide explains all the concepts behind PL/SQL and illustrates every facet of the language. Good programming style is stressed throughout and supported by numerous examples. Using this guide, you learn PL/SQL quickly and effectively.
Anyone developing PL/SQL-based applications for Oracle8i will benefit from reading this guide. Written especially for programmers, this comprehensive treatment of PL/SQL will also be of value to systems analysts, project managers, and others interested in database applications. To use this guide effectively, you need a working knowledge of Oracle8i, SQL, and a 3GL such as Ada, C, or COBOL.
You will not find installation instructions or system-specific information in this guide. For that kind of information, see the Oracle installation or user's guide for your system.
The PL/SQL User's Guide and Reference has 11 chapters and 5 appendices. Chapters 1 through 10 introduce you to PL/SQL and show you how to use its many features. Chapter 11 serves as a reference to PL/SQL commands, syntax, and semantics. Appendices A through E provide sample programs, supplementary technical information, and a list of reserved words.
This chapter surveys the main features of PL/SQL and points out the advantages they offer. It also acquaints you with the basic concepts behind PL/SQL and the general appearance of PL/SQL programs.
This chapter focuses on the small-scale aspects of PL/SQL. It discusses lexical units, scalar datatypes, user-defined subtypes, data conversion, expressions, assignments, block structure, declarations, and scope.
This chapter shows you how to structure the flow of control through a PL/SQL program. It describes conditional, iterative, and sequential control. You learn how to apply simple but powerful control structures such as IF-THEN-ELSE and WHILE-LOOP.
This chapter focuses on the composite datatypes TABLE, VARRAY, and RECORD. You learn how to reference and manipulate whole collections of data, and how to treat related but dissimilar data as a logical unit. You also learn how to improve performance by bulk-binding collections.
This chapter shows you how PL/SQL supports the SQL commands, functions, and operators that let you manipulate Oracle data. You also learn how to manage cursors, process transactions, and safeguard your database.
This chapter provides an in-depth discussion of error reporting and recovery. You learn how to detect and handle errors using PL/SQL exceptions.
This chapter shows you how to write and use subprograms. It discusses procedures, functions, forward declarations, actual and formal parameters, positional and named notation, parameter modes, the NOCOPY compiler hint, parameter default values, aliasing, overloading, invoker rights, and recursion.
This chapter shows you how to bundle related PL/SQL types, items, and subprograms into a package. Once written, your general-purpose package is compiled, then stored in an Oracle database, where its contents can be shared by many applications.
This chapter introduces you to object-oriented programming based on object types, which provide abstract templates for real-world objects. You learn how to define object types and manipulate objects.
This chapter shows you how to use dynamic SQL, an advanced programming technique that makes your applications more flexible and versatile. You learn two simple ways to write programs that can build and process SQL statements "on the fly" at run time.
This chapter uses syntax diagrams to show how commands, parameters, and other language elements are sequenced to form PL/SQL statements. Also, it provides usage notes and short examples to help you become fluent in PL/SQL quickly.
This appendix provides several PL/SQL programs to guide you in writing your own. The sample programs illustrate important concepts and features.
This appendix explains the subtle but important semantic differences between the CHAR and VARCHAR2 base types.
This appendix shows you how to run the PL/SQL Wrapper, a stand-alone utility that enables you to deliver PL/SQL applications without exposing your source code.
Thus appendix explains how PL/SQL resolves references to names in potentially ambiguous SQL and procedural statements.
This appendix lists those words reserved for use by PL/SQL.
This guide follows these conventions:
PL/SQL code examples follow these conventions:
Syntax definitions use a simple variant of Backus-Naur Form (BNF) that includes the following symbols:
Most programming examples in this guide use two sample database tables named dept and emp. Their definitions follow:
CREATE TABLE dept ( deptno NUMBER(2) NOT NULL, dname VARCHAR2(14), loc VARCHAR2(13)); CREATE TABLE emp ( empno NUMBER(4) NOT NULL, ename VARCHAR2(10), job VARCHAR2(9), mgr NUMBER(4), hiredate DATE, sal NUMBER(7,2), comm NUMBER(7,2), deptno NUMBER(2));
Respectively, the dept and emp tables contain the following rows of data:
DEPTNO DNAME LOC ------- ---------- --------- 10 ACCOUNTING NEW YORK 20 RESEARCH DALLAS 30 SALES CHICAGO 40 OPERATIONS BOSTON EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO ----- ------- --------- ------ --------- ------ ------ ------- 7369 SMITH CLERK 7902 17-DEC-80 800 20 7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30 7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30 7566 JONES MANAGER 7839 02-APR-81 2975 20 7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30 7698 BLAKE MANAGER 7839 01-MAY-81 2850 30 7782 CLARK MANAGER 7839 09-JUN-81 2450 10 7788 SCOTT ANALYST 7566 19-APR-87 3000 20 7839 KING PRESIDENT 17-NOV-81 5000 10 7844 TURNER SALESMAN 7698 08-SEP-81 1500 30 7876 ADAMS CLERK 7788 23-MAY-87 1100 20 7900 JAMES CLERK 7698 03-DEC-81 950 30 7902 FORD ANALYST 7566 03-DEC-81 3000 20 7934 MILLER CLERK 7782 23-JAN-82 1300 10
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