PL/SQL User’s Guide and Reference Release 2 (9.2) March 2002 Part No. A96624-01 PL/SQL User’s Guide and Reference, Release 2 (9.2) Part No. A96624-01 Copyright © 1996, 2002 Oracle Corporation. All rights reserved. Primary Author: John Russell Contributing Author: Tom Portfolio Contributors: Shashaanka Agrawal, Cailein Barclay, Dmitri Bronnikov, Sharon Castledine, Thomas Chang, Ravindra Dani, Chandrasekharan Iyer, Susan Kotsovolos, Neil Le, Warren Li, Chris Racicot, Murali Vemulapati, Guhan Viswanathan, Minghui Yang The Programs (which include both the software and documentation) contain proprietary information of Oracle Corporation; they are provided under a license agreement containing restrictions on use and disclosure and are also protected by copyright, patent and other intellectual and industrial property laws. 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Contents Send Us Your Comments ................................................................................................................. xix Preface.......................................................................................................................................................... xxi What’s New in PL/SQL?................................................................................................................... xxxi 1 Overview of PL/SQL Understanding the Main Features of PL/SQL............................................................................... 1-2 Block Structure.............................................................................................................................. 1-2 Variables and Constants .............................................................................................................. 1-3 Cursors ........................................................................................................................................... 1-5 Cursor FOR Loops........................................................................................................................ 1-6 Cursor Variables ........................................................................................................................... 1-6 Attributes ....................................................................................................................................... 1-7 Control Structures ........................................................................................................................ 1-9 Modularity................................................................................................................................... 1-12 Data Abstraction ......................................................................................................................... 1-14 Information Hiding .................................................................................................................... 1-16 Error Handling............................................................................................................................ 1-16 PL/SQL Architecture ........................................................................................................................ 1-17 In the Oracle Database Server................................................................................................... 1-18 In Oracle Tools ............................................................................................................................ 1-20 Advantages of PL/SQL..................................................................................................................... 1-20 Support for SQL.......................................................................................................................... 1-20 iii Support for Object-Oriented Programming............................................................................ 1-21 Better Performance ..................................................................................................................... 1-21 Higher Productivity.................................................................................................................... 1-22 Full Portability............................................................................................................................. 1-23 Tight Integration with SQL ....................................................................................................... 1-23 Tight Security .............................................................................................................................. 1-23 2 Fundamentals of PL/SQL Character Set ........................................................................................................................................ 2-2 Lexical Units......................................................................................................................................... 2-2 Delimiters....................................................................................................................................... 2-3 Identifiers ....................................................................................................................................... 2-4 Literals ............................................................................................................................................ 2-7 Comments.................................................................................................................................... 2-10 Declarations ....................................................................................................................................... 2-11 Using DEFAULT......................................................................................................................... 2-12 Using NOT NULL....................................................................................................................... 2-13 Using %TYPE .............................................................................................................................. 2-13 Using %ROWTYPE..................................................................................................................... 2-14 Restrictions on Declarations...................................................................................................... 2-17 PL/SQL Naming Conventions........................................................................................................ 2-17 Scope and Visibility of PL/SQL Identifiers ................................................................................. 2-19 Variable Assignment ........................................................................................................................ 2-22 Assigning Boolean Values ......................................................................................................... 2-22 Assigning a SQL Query Result to a PL/SQL Variable.......................................................... 2-23 PL/SQL Expressions and Comparisons ........................................................................................ 2-23 Logical Operators........................................................................................................................ 2-25 Boolean Expressions................................................................................................................... 2-28 CASE Expressions......................................................................................................................