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Oracle is not responsible for any loss or damage of any sort that you may incur from dealing with any third party. iii Contents Send Us Your Comments xvii Preface xix Audience xix Documentation Accessibility xix Structure xx PL/SQL Sample Programs xxi Related Documents xxii Conventions xxii What's New in PL/SQL? xxv New Features in PL/SQL for Oracle Database 10g Release 2 (10.2) xxv New Features in PL/SQL for Oracle Database 10g Release 1 (10.1) xxvi 1 Overview of PL/SQL Advantages of PL/SQL 1-1 Tight Integration with SQL 1-2 Better Performance 1-2 Higher Productivity 1-3 Full Portability 1-3 Tight Security 1-3 Access to Pre-defined Packages 1-4 Support for Object-Oriented Programming 1-4 Support for Developing Web Applications and Pages 1-4 Understanding the Main Features of PL/SQL 1-4 Understanding PL/SQL Block Structure 1-4 Understanding PL/SQL Variables and Constants 1-5 Declaring Variables 1-5 Assigning Values to a Variable 1-6 Bind Variables 1-7 Declaring Constants 1-7 Processing Queries with PL/SQL 1-8 Declaring PL/SQL Subprograms 1-8 Declaring Datatypes for PL/SQL Variables 1-8 %TYPE 1-8 iv %ROWTYPE 1-9 Understanding PL/SQL Control Structures 1-9 Conditional Control 1-10 Iterative Control 1-10 Sequential Control 1-12 Understanding Conditional Compilation 1-12 Writing Reusable PL/SQL Code 1-13 Subprograms: Procedures and Functions 1-13 Packages: APIs Written in PL/SQL 1-13 Inputting and Outputting Data with PL/SQL 1-15 Understanding PL/SQL Data Abstraction 1-16 Cursors 1-16 Collections 1-16 Records 1-16 Object Types 1-17 Understanding PL/SQL Error Handling 1-18 PL/SQL Architecture 1-18 In the Oracle Database Server 1-19 Anonymous Blocks 1-19 Stored Subprograms 1-19 Database Triggers 1-20 In Oracle Tools 1-21 2 Fundamentals of the PL/SQL Language Character Sets and Lexical Units 2-1 Delimiters 2-2 Identifiers 2-3 Reserved Words 2-4 Predefined Identifiers 2-4 Quoted Identifiers 2-4 Literals 2-4 Numeric Literals 2-5 Character Literals 2-6 String Literals 2-6 BOOLEAN Literals 2-7 Datetime Literals 2-7 Comments 2-7 Single-Line Comments 2-7 Multi-line Comments 2-8 Restrictions on Comments 2-8 Declarations 2-8 Constants 2-9 Using DEFAULT 2-9 Using NOT NULL 2-9 Using the %TYPE Attribute 2-10 Using the %ROWTYPE Attribute 2-11 Aggregate Assignment 2-12 v Using Aliases 2-12 Restrictions on Declarations 2-13 PL/SQL Naming Conventions 2-13 Scope and Visibility of PL/SQL Identifiers 2-15 Assigning Values to Variables 2-18 Assigning BOOLEAN Values 2-19 Assigning a SQL Query Result to a PL/SQL Variable 2-19 PL/SQL Expressions and Comparisons 2-19 Logical Operators 2-20 Order of Evaluation 2-21 Short-Circuit Evaluation 2-21 Comparison Operators 2-22 Relational Operators 2-22 IS NULL Operator 2-23 LIKE Operator 2-23 BETWEEN Operator 2-23 IN Operator 2-23 Concatenation Operator 2-23 BOOLEAN Expressions 2-24 BOOLEAN Arithmetic Expressions 2-24 BOOLEAN Character Expressions 2-24 BOOLEAN Date Expressions 2-25 Guidelines for PL/SQL BOOLEAN Expressions 2-25 CASE Expressions 2-26 Simple CASE expression 2-26 Searched CASE Expression 2-27 Handling Null Values in Comparisons and Conditional Statements 2-27 NULLs and the NOT Operator 2-28 Conditional Compilation 2-30 How Does Conditional Compilation Work? 2-31 Conditional Compilation Control Tokens 2-31 Using Conditional Compilation Selection Directives 2-31 Using Conditional Compilation Error Directives 2-31 Using Conditional Compilation Inquiry Directives 2-31 Using Predefined Inquiry Directives With Conditional Compilation 2-32 Using Static Expressions with Conditional Compilation 2-33 Setting the PLSQL_CCFLAGS Initialization Parameter 2-34 Using DBMS_DB_VERSION Package Constants 2-35 Conditional Compilation Examples 2-35 Using Conditional Compilation to Specify Code for Database Versions 2-35 Using DBMS_PREPROCESSOR Procedures to Print or Retrieve Source Text 2-36 Conditional Compilation Restrictions 2-37 Using PL/SQL to Create Web Applications and Server Pages 2-38 PL/SQL Web Applications 2-38 PL/SQL Server Pages 2-38 Summary of PL/SQL Built-In Functions 2-38 vi 3 PL/SQL Datatypes Overview of Predefined PL/SQL Datatypes 3-1 PL/SQL Number Types 3-2 BINARY_INTEGER Datatype 3-2 BINARY_FLOAT and BINARY_DOUBLE Datatypes 3-2 NUMBER Datatype 3-3 PLS_INTEGER Datatype 3-4 PL/SQL Character and String Types 3-4 CHAR Datatype 3-4 LONG and LONG RAW Datatypes 3-5 RAW Datatype 3-6 ROWID and UROWID Datatype 3-6 VARCHAR2 Datatype 3-8 PL/SQL National Character Types 3-9 Comparing UTF8 and AL16UTF16 Encodings 3-9 NCHAR Datatype 3-9 NVARCHAR2 Datatype 3-10 PL/SQL LOB Types 3-10 BFILE Datatype 3-11 BLOB Datatype 3-11 CLOB Datatype 3-11 NCLOB Datatype 3-12 PL/SQL Boolean Types 3-12 BOOLEAN Datatype 3-12 PL/SQL Date, Time, and Interval Types 3-12 DATE Datatype 3-13 TIMESTAMP Datatype 3-13 TIMESTAMP WITH TIME ZONE Datatype 3-14 TIMESTAMP WITH LOCAL TIME ZONE Datatype 3-15 INTERVAL YEAR TO MONTH Datatype 3-16 INTERVAL DAY TO SECOND Datatype 3-16 Datetime and Interval Arithmetic 3-17 Avoiding Truncation Problems Using Date and Time Subtypes 3-17 Overview of PL/SQL Subtypes 3-17 Defining Subtypes 3-18 Using Subtypes 3-18 Type Compatibility With Subtypes 3-19 Constraints and Default Values With Subtypes 3-20 Converting PL/SQL Datatypes 3-21 Explicit Conversion 3-21 Implicit Conversion 3-21 Choosing Between Implicit and Explicit Conversion 3-23 DATE Values 3-23 RAW and LONG RAW Values 3-23 Differences between the CHAR and VARCHAR2 Datatypes 3-23 Assigning Character Values 3-23 Comparing Character Values 3-24 vii Inserting Character Values 3-25 Selecting Character Values 3-26 4 Using PL/SQL Control Structures Overview of PL/SQL Control Structures 4-1 Testing Conditions: IF and CASE Statements 4-2 Using the IF-THEN Statement 4-2 Using the IF-THEN-ELSE Statement 4-2 Using the IF-THEN-ELSIF Statement 4-3 Using CASE Statements 4-4 Searched CASE Statement 4-5 Guidelines for PL/SQL Conditional Statements 4-6 Controlling Loop Iterations: LOOP and EXIT Statements 4-7 Using the LOOP Statement 4-7 Using the EXIT Statement 4-7 Using the EXIT-WHEN Statement 4-8 Labeling a PL/SQL Loop 4-8 Using the WHILE-LOOP Statement 4-9 Using the FOR-LOOP Statement 4-9 How PL/SQL Loops Iterate 4-10 Dynamic Ranges for Loop Bounds 4-11 Scope of the Loop Counter Variable 4-11 Using the EXIT Statement in a FOR Loop 4-12 Sequential Control: GOTO and NULL Statements 4-13 Using the GOTO Statement 4-13 Restrictions on the GOTO Statement 4-15 Using the NULL Statement 4-15 5 Using PL/SQL Collections and Records What are PL/SQL Collections and Records? 5-1 Understanding PL/SQL Collections 5-2 Understanding Nested Tables 5-2 Understanding Varrays 5-3 Understanding Associative Arrays (Index-By Tables) 5-3 How Globalization Settings Affect VARCHAR2 Keys for Associative Arrays 5-4 Understanding PL/SQL Records 5-5 Choosing Which PL/SQL Collection Types to Use 5-5 Choosing Between Nested Tables and Associative Arrays 5-5 Choosing Between Nested Tables and Varrays 5-5 Defining Collection Types and Declaring Collection Variables 5-6 Declaring PL/SQL Collection Variables 5-7 Initializing and Referencing Collections 5-10 Referencing Collection Elements 5-11 Assigning Collections 5-12 Comparing Collections 5-16 Using Multilevel Collections 5-18 viii Using Collection Methods 5-19 Checking If a Collection Element Exists (EXISTS Method) 5-19 Counting the Elements in a Collection (COUNT Method) 5-20 Checking the Maximum Size of a Collection (LIMIT Method) 5-20 Finding the First or Last Collection Element (FIRST and LAST Methods) 5-21 Looping Through Collection Elements (PRIOR and NEXT Methods) 5-22 Increasing the Size of a Collection (EXTEND Method) 5-23 Decreasing the Size of a Collection (TRIM Method) 5-24 Deleting Collection Elements (DELETE Method) 5-25 Applying Methods to Collection Parameters 5-26 Avoiding Collection Exceptions 5-27 Defining and Declaring Records 5-29 Using Records as Procedure Parameters and Function Return Values 5-31 Assigning Values to Records 5-32 Comparing Records 5-33 Inserting PL/SQL Records into the Database 5-33 Updating the Database with PL/SQL Record Values 5-34 Restrictions on Record Inserts and Updates 5-35 Querying Data into Collections of Records 5-36 6 Performing SQL Operations from PL/SQL Overview of SQL Support in PL/SQL 6-1 Data Manipulation 6-1 Transaction Control 6-3 SQL Functions 6-3 SQL Pseudocolumns 6-3 SQL Operators 6-6 Managing Cursors in PL/SQL 6-6 Implicit Cursors 6-6 Attributes of Implicit Cursors 6-7 Guidelines for Using Attributes of Implicit Cursors 6-8 Explicit Cursors 6-8 Declaring a Cursor 6-8 Opening a Cursor 6-9 Fetching with a Cursor 6-9 Fetching Bulk Data with a Cursor 6-11 Closing a Cursor 6-12 Attributes of Explicit Cursors 6-12 Querying Data with PL/SQL 6-14 Selecting At Most One Row: SELECT INTO Statement 6-14 Selecting Multiple Rows: BULK COLLECT Clause 6-15 Looping Through Multiple Rows: Cursor FOR Loop 6-15 Performing Complicated Query Processing: Explicit Cursors 6-15 Querying Data with PL/SQL: Implicit Cursor FOR Loop 6-16 Querying Data with PL/SQL: Explicit Cursor FOR Loops 6-16 Defining Aliases for Expression Values in a Cursor FOR Loop 6-17 Using Subqueries 6-17 ix Using Correlated Subqueries 6-18 Writing Maintainable PL/SQL Queries 6-19 Using Cursor Variables (REF CURSORs) 6-20 What Are Cursor Variables (REF CURSORs)? 6-20 Why Use Cursor Variables? 6-20 Declaring REF CURSOR Types and Cursor Variables 6-20 Passing Cursor Variables As Parameters 6-22 Controlling Cursor Variables: OPEN-FOR, FETCH, and CLOSE 6-22 Opening a Cursor Variable 6-22 Using a Cursor Variable as a Host Variable 6-24 Fetching from a Cursor Variable 6-25 Closing a Cursor Variable 6-26 Reducing Network Traffic When Passing Host Cursor Variables to PL/SQL 6-26 Avoiding Errors with Cursor Variables 6-27 Restrictions on Cursor Variables 6-27 Using Cursor Expressions 6-28 Restrictions on Cursor Expressions 6-28 Example of Cursor Expressions 6-29 Constructing REF CURSORs with Cursor Subqueries 6-29 Overview of Transaction Processing in PL/SQL 6-30 Using COMMIT in PL/SQL 6-30 Using ROLLBACK in PL/SQL 6-31 Using SAVEPOINT in PL/SQL 6-31 How Oracle Does Implicit Rollbacks 6-32 Ending Transactions 6-33 Setting Transaction Properties with SET TRANSACTION 6-33 Restrictions on SET TRANSACTION 6-34 Overriding Default Locking 6-34 Doing Independent Units of Work with Autonomous Transactions 6-37 Advantages of Autonomous Transactions 6-37 Defining Autonomous Transactions 6-37 Comparison of Autonomous Transactions and Nested Transactions 6-39 Transaction Context 6-39 Transaction Visibility 6-39 Controlling Autonomous Transactions 6-39 Using Autonomous Triggers 6-41 Calling Autonomous Functions from SQL 6-42 7 Performing SQL Operations with Native Dynamic SQL Why Use Dynamic SQL with PL/SQL? 7-1 Using the EXECUTE IMMEDIATE Statement in PL/SQL 7-2 Specifying Parameter Modes for Bind Variables in Dynamic SQL Strings 7-4 Using Bulk Dynamic SQL in PL/SQL 7-5 Using Dynamic SQL with Bulk SQL 7-5 Examples of Dynamic Bulk Binds 7-6 Guidelines for Using Dynamic SQL with PL/SQL 7-7 Building a Dynamic Query with Dynamic SQL 7-7 x When to Use or Omit the Semicolon with Dynamic SQL 7-7 Improving Performance of Dynamic SQL with Bind Variables 7-8 Passing Schema Object Names As Parameters 7-8 Using Duplicate Placeholders with Dynamic SQL 7-9 Using Cursor Attributes with Dynamic SQL 7-9 Passing Nulls to Dynamic SQL 7-10 Using Database Links with Dynamic SQL 7-10 Using Invoker Rights with Dynamic SQL 7-11 Using Pragma RESTRICT_REFERENCES with Dynamic SQL 7-11 Avoiding Deadlocks with Dynamic SQL 7-11 Backward Compatibility of the USING Clause 7-12 Using Dynamic SQL With PL/SQL Records and Collections 7-12 8 Using PL/SQL Subprograms What Are Subprograms? 8-1 Advantages of PL/SQL Subprograms 8-2 Understanding PL/SQL Procedures 8-3 Understanding PL/SQL Functions 8-4 Using the RETURN Statement 8-5 Declaring Nested PL/SQL Subprograms 8-5 Passing Parameters to PL/SQL Subprograms 8-6 Actual Versus Formal Subprogram Parameters 8-6 Using Positional, Named, or Mixed Notation for Subprogram Parameters 8-7 Specifying Subprogram Parameter Modes 8-7 Using the IN Mode 8-7 Using the OUT Mode 8-8 Using the IN OUT Mode 8-8 Summary of Subprogram Parameter Modes 8-9 Using Default Values for Subprogram Parameters 8-9 Overloading Subprogram Names 8-10 Guidelines for Overloading with Numeric Types 8-10 Restrictions on Overloading 8-11 How Subprogram Calls Are Resolved 8-12 How Overloading Works with Inheritance 8-14 Using Invoker's Rights Versus Definer's Rights (AUTHID Clause) 8-15 Advantages of Invoker's Rights 8-16 Specifying the Privileges for a Subprogram with the AUTHID Clause 8-16 Who Is the Current User During Subprogram Execution? 8-16 How External References Are Resolved in Invoker's Rights Subprograms 8-17 The Need for Template Objects in Invoker's Rights Subprograms 8-17 Overriding Default Name Resolution in Invoker's Rights Subprograms 8-17 Granting Privileges on Invoker's Rights Subprograms 8-18 Granting Privileges on an Invoker's Rights Subprogram: Example 8-18 Using Roles with Invoker's Rights Subprograms 8-19 Using Views and Database Triggers with Invoker's Rights Subprograms 8-19 Using Database Links with Invoker's Rights Subprograms 8-19 Using Object Types with Invoker's Rights Subprograms 8-20 [...]... Qualifying References to Object Attributes and Methods References to Attributes and Methods References to Row Expressions C PL/SQL Program Limits D B-1 B-2 B-3 B-3 B-4 B-4 B-5 B-5 B-5 B-6 B-6 B-7 PL/SQL Reserved Words and Keywords Index xv xvi Send Us Your Comments Oracle Database PL/SQL User’s Guide and Reference 10g Release 2 (10.2) B14261-01 Oracle welcomes your comments and. .. of PL/SQL programming, in particular details for triggers and stored procedures, see Oracle Database Application Developer's Guide - Fundamentals For information about PL/SQL packages provided with the Oracle database, see Oracle Database PL/SQL Packages and Types Reference For information on object-oriented programming using both PL/SQL and SQL features, see Oracle Database Application Developer's Guide. .. Appendix B, "How PL/SQL Resolves Identifier Names" Explains how PL/SQL resolves references to names in potentially ambiguous SQL and procedural statements Appendix C, "PL/SQL Program Limits" Explains the compile-time and runtime limits imposed by PL/SQL Appendix D, "PL/SQL Reserved Words and Keywords" Lists the words that are reserved for use by PL/SQL PL/SQL Sample Programs You can install the PL/SQL sample... to bundle related PL/SQL types, items, and subprograms into a package Packages define APIs that can be reused by many applications Chapter 10, "Handling PL/SQL Errors" Shows how to detect and handle PL/SQL errors using exceptions and handlers Chapter 11, "Tuning PL/SQL Applications for Performance" Discusses how to improve performance for PL/SQL- based applications Chapter 12, "Using PL/SQL With Object... ELSE SQL END IF; SQL Oracle Database with PL/SQL RPC Oracle Database with PL/SQL and Stored Procedures Higher Productivity PL/SQL lets you write very compact code for manipulating data In the same way that scripting languages such as Perl can read, transform, and write data from files, PL/SQL can query, transform, and update data in a database PL/SQL saves time on design and debugging by offering a... HTF and HTP Packages 9-10 About the UTL_FILE Package 9-10 About the UTL_HTTP Package 9-10 About the UTL_SMTP Package 9-10 Guidelines for Writing Packages 9-10 Separating Cursor Specs and Bodies with Packages 9-11 10 Handling PL/SQL Errors Overview of PL/SQL Runtime Error Handling Guidelines for Avoiding and Handling PL/SQL. .. stored procedures execute in the database server, a single call over the network can start a large job This division of work reduces network traffic and improves response times Stored procedures are cached and shared among users, which lowers memory requirements and invocation overhead 1-2 Oracle Database PL/SQL User’s Guide and Reference Advantages of PL/SQL Figure 1–1 PL/SQL Boosts Performance SQL SQL... structures such as IF-THEN-ELSE, CASE, and WHILE-LOOP Chapter 5, "Using PL/SQL Collections and Records" Discusses the composite datatypes TABLE, VARRAY, and RECORD You learn how to reference and manipulate whole collections of data and group data of different types together Chapter 6, "Performing SQL Operations from PL/SQL" Shows how PL/SQL supports the SQL commands, functions, and operators for manipulating... object types, see Oracle Database Application Developer's Guide - Object-Relational Features Support for Developing Web Applications and Pages You can use PL/SQL to develop Web applications and Server Pages (PSPs) For an overview of the use of PL/SQL with the Web, see "Using PL/SQL to Create Web Applications and Server Pages" on page 2-38 Understanding the Main Features of PL/SQL PL/SQL combines the data-manipulating... date and time, and the system change number that represents the database state at a point in time See Example 3–2, "Using the SCN_TO_TIMESTAMP and TIMESTAMP_TO_SCN Functions" on page 3-14 See "Summary of PL/SQL Built-In Functions" on page 2-38 xxviii 1 Overview of PL/SQL This chapter introduces the main features of the PL/SQL language It shows how PL/SQL meets the challenges of database programming, and . Oracle® Database PL/SQL User's Guide and Reference 10g Release 2 (10.2) B14261-01 June 2005 Oracle Database PL/SQL User’s Guide and Reference 10g Release 2 (10.2). Packages 9-11 10 Handling PL/SQL Errors Overview of PL/SQL Runtime Error Handling 10-1 Guidelines for Avoiding and Handling PL/SQL Errors and Exceptions 10-2 Advantages of PL/SQL Exceptions 10-3 Summary. SQL With PL/SQL Records and Collections 7-12 8 Using PL/SQL Subprograms What Are Subprograms? 8-1 Advantages of PL/SQL Subprograms 8-2 Understanding PL/SQL Procedures 8-3 Understanding PL/SQL Functions