1. [Appendix A] What's on the Companion Disk?

2. Table of Contents A. What's on the Companion Disk?..................................................................................................................2 A.1 Installing the Guide...........................................................................................................................2 ...............................................................................................................................................................................3 A.2 Using the Guide................................................................................................................................3 ...............................................................................................................................................................................5 B. Calling Stored Procedures from PL/SQL Version 1.1................................................................................6 B.1 Using Stubs to Talk to ServerSide PL/SQL....................................................................................7 ...............................................................................................................................................................................9 B.2 Restrictions on Calling Stored Procedures........................................................................................9 B.2.1 No ServerSide PL/SQL Datatypes..................................................................................9 B.2.2 No Direct Stored Package Variable References..............................................................10 B.2.3 No Direct Remote Procedure Calls.................................................................................12 B.2.4 No Default Parameter Values..........................................................................................12 .............................................................................................................................................................................14 C. BuiltIn Packages........................................................................................................................................15 C.1 Using the Builtin Packages...........................................................................................................16 .............................................................................................................................................................................18 C.2 DBMS_ALERT...............................................................................................................................18 C.2.1 The REGISTER procedure.............................................................................................18 C.2.2 The REMOVE procedure................................................................................................18 C.2.3 The REMOVEALL procedure........................................................................................18 C.2.4 The SET_DEFAULTS procedure...................................................................................18 C.2.5 The SIGNAL procedure..................................................................................................18 C.2.6 The WAITANY procedure.............................................................................................19 C.2.7 The WAITONE procedure..............................................................................................19 .............................................................................................................................................................................20 C.3 Oracle AQ, the Advanced Queueing Facility..................................................................................20 C.3.1 DBMS_AQ (PL/SQL 8 Only).........................................................................................20 C.3.2 DBMS_AQADM (PL/SQL 8 Only)...............................................................................21 .............................................................................................................................................................................24 C.4 DBMS_DDL...................................................................................................................................24 C.4.1 The ALTER_COMPILE procedure................................................................................24 C.4.2 The ANALYZE_OBJECT procedure.............................................................................24 .............................................................................................................................................................................25 C.5 DBMS_ JOB...................................................................................................................................25 C.5.1 The BROKEN procedure................................................................................................25 C.5.2 The CHANGE procedure................................................................................................25 C.5.3 The INTERVAL procedure.............................................................................................25 C.5.4 The ISUBMIT procedure................................................................................................25 C.5.5 The NEXT_DATE procedure.........................................................................................26 C.5.6 The REMOVE procedure................................................................................................26 C.5.7 The RUN procedure........................................................................................................26 C.5.8 The SUBMIT procedure.................................................................................................26 C.5.9 The USER_EXPORT procedure.....................................................................................26 C.5.10 The WHAT procedure...................................................................................................26 .............................................................................................................................................................................28 C.6 DBMS_LOB (PL/SQL8 Only).......................................................................................................28 C.6.1 The APPEND procedure.................................................................................................28 C.6.2 The COMPARE function................................................................................................28 C.6.3 The COPY procedure......................................................................................................29 [Appendix A] What's on the Companion Disk? i

3. Table of Contents C.6.4 The ERASE procedure....................................................................................................29 C.6.5 The FILECLOSE procedure...........................................................................................29 C.6.6 The FILECLOSEALL procedure....................................................................................29 C.6.7 The FILEEXISTS function.............................................................................................29 C.6.8 The FILEGETNAME procedure.....................................................................................29 C.6.9 The FILEISOPEN function.............................................................................................30 C.6.10 The FILEOPEN procedure............................................................................................30 C.6.11 The GETLENGTH function.........................................................................................30 C.6.12 The INSTR function......................................................................................................30 C.6.13 The READ procedure....................................................................................................30 C.6.14 The SUBSTR function..................................................................................................31 C.6.15 The TRIM procedure.....................................................................................................31 C.6.16 The WRITE procedure..................................................................................................31 .............................................................................................................................................................................33 C.7 DBMS_LOCK.................................................................................................................................33 C.7.1 The ALLOCATE_UNIQUE procedure..........................................................................33 C.7.2 The CONVERT function................................................................................................33 C.7.3 The RELEASE function..................................................................................................34 C.7.4 The REQUEST function.................................................................................................34 C.7.5 The SLEEP procedure.....................................................................................................34 .............................................................................................................................................................................36 C.8 DBMS_MAIL.................................................................................................................................36 C.8.1 The SEND procedure......................................................................................................36 .............................................................................................................................................................................37 C.9 DBMS_OUTPUT............................................................................................................................37 C.9.1 The DISABLE procedure................................................................................................37 C.9.2 The ENABLE procedure.................................................................................................37 C.9.3 The GET_LINE procedure..............................................................................................37 C.9.4 The GET_LINES procedure...........................................................................................37 C.9.5 The NEW_LINE procedure............................................................................................37 C.9.6 The PUT procedure.........................................................................................................38 C.9.7 The PUT_LINE procedure..............................................................................................38 .............................................................................................................................................................................39 C.10 DBMS_PIPE.................................................................................................................................39 C.10.1 The CREATE_PIPE function.......................................................................................39 C.10.2 The NEXT_ITEM_TYPE function...............................................................................39 C.10.3 The PACK_MESSAGE procedure...............................................................................40 C.10.4 The PURGE procedure.................................................................................................40 C.10.5 The RECEIVE_MESSAGE function............................................................................40 C.10.6 The REMOVE_PIPE function......................................................................................40 C.10.7 The RESET_BUFFER procedure.................................................................................40 C.10.8 The SEND_MESSAGE function..................................................................................41 C.10.9 The UNIQUE_SESSION_NAME function..................................................................41 C.10.10 The UNPACK_MESSAGE procedure.......................................................................41 .............................................................................................................................................................................42 C.11 DBMS_ROWID (PL/SQL8 Only)................................................................................................42 C.11.1 The ROWID_CREATE function..................................................................................42 C.11.2 The ROWID_INFO procedure......................................................................................42 C.11.3 The ROWID_TYPE function........................................................................................42 C.11.4 The ROWID_OBJECT function...................................................................................42 C.11.5 The ROWID_RELATIVE_FNO function....................................................................43 C.11.6 The ROWID_BLOCK_NUMBER function.................................................................43 [Appendix A] What's on the Companion Disk? ii

4. Table of Contents C.11.7 The ROWID_ROW_NUMBER function.....................................................................43 C.11.8 The ROWID_TO_ABSOLUTE_FNO function...........................................................43 C.11.9 The ROWID_TO_EXTENDED function.....................................................................43 C.11.10 The ROWID_TO_RESTRICTED function................................................................43 C.11.11 The ROWID_VERIFY function.................................................................................43 .............................................................................................................................................................................45 C.12 DBMS_SESSION.........................................................................................................................45 C.12.1 The CLOSE_DATABASE_LINK procedure...............................................................45 C.12.2 The IS_ROLE_ENABLED function.............................................................................45 C.12.3 The RESET_PACKAGE procedure.............................................................................45 C.12.4 The SET_LABEL procedure.........................................................................................45 C.12.5 The SET_NLS_LABEL procedure...............................................................................45 C.12.6 The SET_NLS procedure..............................................................................................45 C.12.7 The SET_ROLE procedure...........................................................................................46 C.12.8 The SET_SQL_TRACE procedure...............................................................................46 C.12.9 The UNIQUE_SESSION_ID function.........................................................................46 .............................................................................................................................................................................47 C.13 DBMS_SNAPSHOT.....................................................................................................................47 C.13.1 The DROP_SNAPSHOT procedure.............................................................................47 C.13.2 The GET_LOG_AGE procedure..................................................................................47 C.13.3 The PURGE_LOG procedure.......................................................................................47 C.13.4 The REFRESH procedure.............................................................................................47 C.13.5 The REFRESH_ALL procedure...................................................................................48 C.13.6 The SET_UP procedure................................................................................................48 C.13.7 The WRAP_UP procedure............................................................................................48 .............................................................................................................................................................................49 C.14 DBMS_SQL..................................................................................................................................49 C.14.1 The BIND_ARRAY procedure.....................................................................................49 C.14.2 The BIND_VARIABLE procedure...............................................................................49 C.14.3 The CLOSE_CURSOR procedure................................................................................50 C.14.4 The COLUMN_VALUE procedure..............................................................................50 C.14.5 The DEFINE_COLUMN procedure.............................................................................51 C.14.6 The EXECUTE function...............................................................................................51 C.14.7 The EXECUTE_AND_FETCH function......................................................................52 C.14.8 The FETCH_ROWS function.......................................................................................52 C.14.9 The IS_OPEN function.................................................................................................52 C.14.10 The LAST_ERROR_POSITION function..................................................................52 C.14.11 The LAST_ROW_COUNT function..........................................................................52 C.14.12 The LAST_ROW_ID function....................................................................................52 C.14.13 The LAST_SQL_FUNCTION_CODE function.........................................................52 C.14.14 The OPEN_CURSOR function...................................................................................53 C.14.15 The PARSE procedure................................................................................................53 C.14.16 The VARIABLE_VALUE procedure.........................................................................53 .............................................................................................................................................................................54 C.15 DBMS_TRANSACTION.............................................................................................................54 C.15.1 The ADVISE_COMMIT procedure.............................................................................54 C.15.2 The ADVISE_NOTHING procedure............................................................................54 C.15.3 The ADVISE_ROLLBACK procedure........................................................................54 C.15.4 The COMMIT procedure..............................................................................................55 C.15.5 The COMMIT_COMMENT procedure........................................................................55 C.15.6 The COMMIT_FORCE procedure...............................................................................55 C.15.7 The READ_ONLY procedure.......................................................................................55 [Appendix A] What's on the Companion Disk? iii

5. Table of Contents C.15.8 The READ_WRITE procedure.....................................................................................55 C.15.9 The ROLLBACK procedure.........................................................................................56 C.15.10 The ROLLBACK_FORCE procedure........................................................................56 C.15.11 The ROLLBACK_SAVEPOINT procedure...............................................................56 C.15.12 The SAVEPOINT procedure......................................................................................56 C.15.13 The USE_ROLLBACK_SEGMENT procedure.........................................................56 C.15.14 The BEGIN_DISCRETE_TRANSACTION procedure.............................................56 C.15.15 The PURGE_MIXED procedure................................................................................57 C.15.16 The PURGE_LOST_DB procedure............................................................................57 C.15.17 The LOCAL_TRANSACTION_ID function.............................................................57 C.15.18 The STEP_ID function................................................................................................57 .............................................................................................................................................................................59 C.16 DBMS_UTILITY..........................................................................................................................59 C.16.1 The ANALYZE_SCHEMA procedure.........................................................................59 C.16.2 The COMMA_TO_TABLE procedure.........................................................................59 C.16.3 The COMPILE_SCHEMA procedure..........................................................................59 C.16.4 The FORMAT_CALL_STACK function.....................................................................59 C.16.5 The FORMAT_ERROR_STACK function..................................................................59 C.16.6 The GET_TIME function..............................................................................................60 C.16.7 The IS_PARALLEL_SERVER function......................................................................60 C.16.8 The NAME_RESOLVE procedure...............................................................................60 C.16.9 The NAME_TOKENIZE procedure.............................................................................60 C.16.10 The PORT_STRING function.....................................................................................61 C.16.11 The TABLE_TO_COMMA procedure.......................................................................61 .............................................................................................................................................................................62 C.17 UTL_FILE.....................................................................................................................................62 C.17.1 Setting Up UTL_FILE..................................................................................................62 .............................................................................................................................................................................65 1. Introduction to PL/SQL...............................................................................................................................66 1.1 What Is PL/SQL?.............................................................................................................................66 .............................................................................................................................................................................68 1.2 The Concept of Programming in Oracle Applications....................................................................68 .............................................................................................................................................................................70 1.3 The Origins of PL/SQL....................................................................................................................70 1.3.1 Improved Application Portability with PL/SQL..............................................................70 1.3.2 Improved Execution Authority and Transaction Integrity with PL/SQL........................71 .............................................................................................................................................................................72 1.4 PL/SQL Versions.............................................................................................................................72 1.4.1 Working with Multiple Versions of PL/SQL..................................................................72 1.4.2 How This Book Handles Different Versions of PL/SQL................................................73 1.4.3 PL/SQL Version 2.0........................................................................................................73 1.4.4 PL/SQL Release 2.1.........................................................................................................80 1.4.5 PL/SQL Release 2.2.........................................................................................................82 1.4.6 PL/SQL Release 2.3.........................................................................................................83 1.4.7 PL/SQL Version 8.0........................................................................................................84 1.4.8 PL/SQL Release 1.1.........................................................................................................86 .............................................................................................................................................................................88 1.5 Advice for Oracle Programmers......................................................................................................88 1.5.1 Take a Creative, Even Radical Approach........................................................................88 1.5.2 Get Ready to Establish New Habits.................................................................................88 1.5.3 Assume that PL/SQL Has What You Need.....................................................................89 [Appendix A] What's on the Companion Disk? iv

6. Table of Contents 1.5.4 Share Your Ideas..............................................................................................................90 .............................................................................................................................................................................91 1.6 A Few of My Favorite (PL/SQL) Things........................................................................................91 1.6.1 Anchored declarations.....................................................................................................91 1.6.2 Builtin functions............................................................................................................91 1.6.3 Builtin packages............................................................................................................91 1.6.4 The cursor FOR loop.......................................................................................................92 1.6.5 Scoping with nested blocks..............................................................................................92 1.6.6 Module overloading.........................................................................................................92 1.6.7 Local modules..................................................................................................................93 1.6.8 Packages...........................................................................................................................93 .............................................................................................................................................................................95 1.7 Best Practices for PL/SQL Excellence............................................................................................95 1.7.1 Write as Little Code as Possible......................................................................................95 1.7.2 Synchronize Program and Data Structures......................................................................96 1.7.3 Center All Development Around Packages.....................................................................97 1.7.4 Standardize Your PL/SQL Development Environment...................................................98 1.7.5 Structured Code and Other Best Practices.......................................................................98 ...........................................................................................................................................................................101 2. PL/SQL Language Fundamentals.............................................................................................................102 2.1 The PL/SQL Character Set............................................................................................................102 ...........................................................................................................................................................................104 2.2 Identifiers.......................................................................................................................................104 2.2.1 Reserved Words.............................................................................................................105 2.2.2 Whitespace and Keywords.............................................................................................106 ...........................................................................................................................................................................107 2.3 Literals...........................................................................................................................................107 2.3.1 Embedding Single Quotes Inside a String.....................................................................107 2.3.2 Numeric Literals............................................................................................................108 2.3.3 Boolean Literals.............................................................................................................108 ...........................................................................................................................................................................110 2.4 The Semicolon Delimiter...............................................................................................................110 ...........................................................................................................................................................................111 2.5 Comments......................................................................................................................................111 2.5.1 SingleLine Comment Syntax.......................................................................................111 2.5.2 Multiline Comment Syntax............................................................................................111 ...........................................................................................................................................................................113 2.6 The PRAGMA Keyword...............................................................................................................113 ...........................................................................................................................................................................114 2.7 Block Structure..............................................................................................................................114 2.7.1 Sections of the PL/SQL Block.......................................................................................114 2.7.2 Scope of a Block............................................................................................................115 2.7.3 Nested Blocks................................................................................................................115 ...........................................................................................................................................................................117 3. Effective Coding Style.................................................................................................................................118 3.1 Fundamentals of Effective Layout.................................................................................................118 3.1.1 Revealing Logical Structure with Indentation...............................................................119 3.1.2 Using Case to Aid Readability.......................................................................................120 3.1.3 The UPPERlower Style...............................................................................................120 3.1.4 Formatting Single Statements........................................................................................121 [Appendix A] What's on the Companion Disk? v

7. Table of Contents 3. Effective Coding Style 3.1.5 Formatting Your Declarations.......................................................................................122 3.1.6 Formatting Multiline Statements...................................................................................123 ...........................................................................................................................................................................126 3.2 Formatting SQL Statements...........................................................................................................126 ...........................................................................................................................................................................129 3.3 Formatting Control Structures.......................................................................................................129 3.3.1 Formatting IF Statements...............................................................................................129 3.3.2 Formatting Loops...........................................................................................................130 3.3.3 Formatting Exception Handlers.....................................................................................131 ...........................................................................................................................................................................133 3.4 Formatting PL/SQL Blocks...........................................................................................................133 ...........................................................................................................................................................................135 3.5 Formatting Packages......................................................................................................................135 ...........................................................................................................................................................................137 3.6 Using Comments Effectively.........................................................................................................137 3.6.1 Comment As You Code.................................................................................................138 3.6.2 Explain the Why Not the How of Your Program............................................138 3.6.3 Make Comments Easy to Enter and Maintain...............................................................139 3.6.4 Maintain Indentation......................................................................................................140 3.6.5 Comment Declaration Statements.................................................................................141 ...........................................................................................................................................................................143 3.7 Documenting the Entire Package...................................................................................................143 3.7.1 Document the Package Specification............................................................................143 3.7.2 Document the Package Body.........................................................................................144 ...........................................................................................................................................................................146 4. Variables and Program Data.....................................................................................................................147 4.1 Identifiers.......................................................................................................................................147 4.1.1 Choose the Right Name.................................................................................................147 4.1.2 Select Readable Names..................................................................................................148 ...........................................................................................................................................................................149 4.2 Scalar Datatypes.............................................................................................................................149 4.2.1 Numeric Datatypes........................................................................................................150 4.2.2 Numeric Subtypes..........................................................................................................152 4.2.3 Character Datatypes.......................................................................................................153 4.2.4 The Boolean Datatype...................................................................................................160 4.2.5 The DateTime Datatype..............................................................................................160 4.2.6 NLS Character Datatypes..............................................................................................161 4.2.7 LOB Datatypes..............................................................................................................162 4.2.8 Conversion Between Datatypes.....................................................................................166 ...........................................................................................................................................................................169 4.3 NULLs in PL/SQL.........................................................................................................................169 4.3.1 NULL Values in Comparisons......................................................................................170 4.3.2 Checking for NULL Values...........................................................................................170 4.3.3 Function Results with NULL Arguments......................................................................171 ...........................................................................................................................................................................173 4.4 Variable Declarations.....................................................................................................................173 4.4.1 Constrained Declarations...............................................................................................173 4.4.2 Declaration Examples....................................................................................................173 4.4.3 Default Values...............................................................................................................174 4.4.4 NOT NULL Clause........................................................................................................175 [Appendix A] What's on the Companion Disk? vi

8. Table of Contents 4.5.1 Benefits of Anchored Declarations................................................................................176 4.5.2 Anchoring at Compile Time..........................................................................................176 4.5.3 Nesting Usages of the %TYPE Attribute......................................................................177 4.5.4 Anchoring to Variables in Other PL/SQL Blocks.........................................................178 4.5.5 Anchoring to NOT NULL Datatypes............................................................................179 ...........................................................................................................................................................................179 4.5 Anchored Declarations...................................................................................................................179 ...........................................................................................................................................................................181 4.6 ProgrammerDefined Subtypes.....................................................................................................181 4.6.1 Declaring Subtypes........................................................................................................181 4.6.2 Examples of Subtype Declarations................................................................................182 4.6.3 Emulating Constrained Subtypes...................................................................................183 ...........................................................................................................................................................................185 4.7 Tips for Creating and Using Variables..........................................................................................185 4.7.1 Establish Clear Variable Naming Conventions.............................................................185 4.7.2 Name Subtypes to SelfDocument Code......................................................................187 4.7.3 Avoid Recycling Variables............................................................................................188 4.7.4 Use Named Constants to Avoid Hardcoding Values.....................................................188 4.7.5 Convert Variables into Named Constants......................................................................189 4.7.6 Remove Unused Variables from Programs...................................................................190 4.7.7 Use %TYPE When a Variable Represents a Column....................................................190 4.7.8 Use %TYPE to Standardize Nondatabase Declarations................................................191 4.7.9 Use Variables to Hide Complex Logic..........................................................................192 ...........................................................................................................................................................................196 5. Conditional and Sequential Control..........................................................................................................197 5.1 Conditional Control Statements.....................................................................................................197 5.1.1 The IFTHEN Combination..........................................................................................197 5.1.2 The IFTHENELSE Combination..............................................................................198 5.1.3 The IFELSIF Combination..........................................................................................199 5.1.4 Nested IF Statements.....................................................................................................203 ...........................................................................................................................................................................205 5.2 Sequential Control Statements.......................................................................................................205 5.2.1 The GOTO Statement....................................................................................................205 5.2.2 The NULL Statement.....................................................................................................208 ...........................................................................................................................................................................211 6. Database Interaction and Cursors............................................................................................................212 6.1 Transaction Management...............................................................................................................212 6.1.1 The COMMIT Statement...............................................................................................213 6.1.2 The ROLLBACK Statement..........................................................................................213 6.1.3 The SAVEPOINT Statement.........................................................................................214 6.1.4 The SET TRANSACTION Statement...........................................................................214 6.1.5 The LOCK TABLE Statement......................................................................................215 ...........................................................................................................................................................................217 6.2 Cursors in PL/SQL.........................................................................................................................217 6.2.1 Types of Cursors............................................................................................................218 6.2.2 Cursor Operations..........................................................................................................218 ...........................................................................................................................................................................220 6.3 Implicit and Explicit Cursors.........................................................................................................220 6.3.1 Implicit Cursors.............................................................................................................220 6.3.2 Drawbacks of Implicit Cursors......................................................................................220 [Appendix A] What's on the Companion Disk? vii

9. Table of Contents 6.3.3 Explicit Cursors.............................................................................................................222 ...........................................................................................................................................................................224 6.4 Declaring Cursors..........................................................................................................................224 6.4.1 The Cursor Name...........................................................................................................224 6.4.2 PL/SQL Variables in a Cursor.......................................................................................225 6.4.3 Identifier Precedence in a Cursor...................................................................................225 6.4.4 The Cursor RETURN Clause........................................................................................226 ...........................................................................................................................................................................229 6.5 Opening Cursors............................................................................................................................229 ...........................................................................................................................................................................231 6.6 Fetching from Cursors...................................................................................................................231 6.6.1 Matching Column List with INTO Clause....................................................................231 6.6.2 Fetching Past the Last Row...........................................................................................233 ...........................................................................................................................................................................234 6.7 Column Aliases in Cursors............................................................................................................234 ...........................................................................................................................................................................236 6.8 Closing Cursors..............................................................................................................................236 6.8.1 Maximum Number of Cursors.......................................................................................236 6.8.2 Closing Local Cursors...................................................................................................237 ...........................................................................................................................................................................238 6.9 Cursor Attributes............................................................................................................................238 6.9.1 The %FOUND Attribute................................................................................................239 6.9.2 The %NOTFOUND Attribute.......................................................................................240 6.9.3 The %ROWCOUNT Attribute......................................................................................240 6.9.4 The %ISOPEN Attribute...............................................................................................241 6.9.5 Implicit SQL Cursor Attributes.....................................................................................241 6.9.6 Differences Between Implicit and Explicit Cursor Attributes.......................................241 ...........................................................................................................................................................................243 6.10 Cursor Parameters........................................................................................................................243 6.10.1 Generalizing Cursors with Parameters........................................................................244 6.10.2 Opening Cursors with Parameters...............................................................................244 6.10.3 Scope of Cursor Parameters.........................................................................................245 6.10.4 Cursor Parameter Modes.............................................................................................245 6.10.5 Default Values for Parameters.....................................................................................245 ...........................................................................................................................................................................246 6.11 SELECT FOR UPDATE in Cursors............................................................................................246 6.11.1 Releasing Locks with COMMIT.................................................................................247 6.11.2 The WHERE CURRENT OF Clause..........................................................................248 6.12.1 Features of Cursor Variables.......................................................................................250 6.12.2 Similarities to Static Cursors.......................................................................................250 6.12.3 Declaring REF CURSOR Types and Cursor Variables...............................................251 6.12.4 Opening Cursor Variables...........................................................................................252 6.12.5 Fetching from Cursor Variables..................................................................................253 6.12.6 Rules for Cursor Variables..........................................................................................254 6.12.7 Passing Cursor Variables as Arguments......................................................................255 6.12.8 Cursor Variable Restrictions........................................................................................257 ...........................................................................................................................................................................260 6.12 Cursor Variables..........................................................................................................................262 ...........................................................................................................................................................................264 6.13 Working with Cursors..................................................................................................................264 6.13.1 Validating Foreign Key Entry with Cursors................................................................264 6.13.2 Managing a Work Queue with SELECT FOR UPDATE............................................266 ...........................................................................................................................................................................270 [Appendix A] What's on the Companion Disk? viii

10. Table of Contents 7. Loops............................................................................................................................................................271 7.1 Loop Basics....................................................................................................................................271 7.1.1 Examples of Different Loops.........................................................................................271 7.1.2 Structure of PL/SQL Loops...........................................................................................272 ...........................................................................................................................................................................274 7.2 The Simple Loop...........................................................................................................................274 7.2.1 Terminating a Simple Loop: EXIT and EXIT WHEN..................................................275 7.2.2 Emulating a REPEAT UNTIL Loop.............................................................................276 ...........................................................................................................................................................................277 7.3 The Numeric FOR Loop................................................................................................................277 7.3.1 Rules for Numeric FOR Loops......................................................................................277 7.3.2 Examples of Numeric FOR Loops.................................................................................278 7.3.3 Handling Nontrivial Increments....................................................................................279 ...........................................................................................................................................................................280 7.4 The Cursor FOR Loop...................................................................................................................280 7.4.1 Example of Cursor FOR Loops.....................................................................................280 7.4.2 The Cursor FOR Loop Record.......................................................................................281 7.4.3 When to Use the Cursor FOR Loop...............................................................................282 ...........................................................................................................................................................................284 7.5 The WHILE Loop..........................................................................................................................284 7.5.1 The Infinite WHILE Loop.............................................................................................285 ...........................................................................................................................................................................286 7.6 Managing Loop Execution.............................................................................................................286 7.6.1 Loop Labels...................................................................................................................286 7.6.2 Loop Scope....................................................................................................................288 ...........................................................................................................................................................................290 7.7 Tips for PL/SQL Loops.................................................................................................................290 7.7.1 Naming Loop Indexes....................................................................................................290 7.7.2 The Proper Way to Say Goodbye..................................................................................291 7.7.3 Avoiding the Phony Loop..............................................................................................293 7.7.4 PL/SQL Loops Versus SQL Processing........................................................................293 8.1 Why Exception Handling?.............................................................................................................296 ...........................................................................................................................................................................297 8. Exception Handlers.....................................................................................................................................298 ...........................................................................................................................................................................300 8.2 The Exception Section...................................................................................................................300 ...........................................................................................................................................................................302 8.3 Types of Exceptions.......................................................................................................................302 8.3.1 Named System Exceptions............................................................................................302 8.3.2 Named ProgrammerDefined Exceptions.....................................................................304 8.3.3 Unnamed System Exceptions........................................................................................305 8.3.4 Unnamed ProgrammerDefined Exceptions.................................................................306 ...........................................................................................................................................................................308 8.4 Determining ExceptionHandling Behavior.................................................................................308 8.4.1 Scope of an Exception...................................................................................................308 8.4.2 Propagation of an Exception..........................................................................................312 ...........................................................................................................................................................................315 8.5 Raising an Exception.....................................................................................................................315 8.5.1 Who Raises the Exception?...........................................................................................315 8.5.2 ReRaising an Exception..............................................................................................316 8.5.3 Exceptions Raised in a Declaration...............................................................................317 [Appendix A] What's on the Companion Disk? ix

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Table of Contents 8.5.4 Exceptions Raised in an Exception Handler..................................................................317 ...........................................................................................................................................................................320 8.6 Handling Exceptions......................................................................................................................320 8.6.1 Combining Multiple Exceptions in a Single Handler....................................................320 8.6.2 Unhandled Exceptions...................................................................................................321 8.6.3 Using SQLCODE and SQLERRM in WHEN OTHERS Clause..................................321 8.6.4 Continuing Past Exceptions...........................................................................................322 ...........................................................................................................................................................................325 8.7 ClientServer Error Communication.............................................................................................325 8.7.1 Using RAISE_APPLICATION_ERROR......................................................................325 8.7.2 RAISE_APPLICATION_ERROR in a database trigger...............................................325 ...........................................................................................................................................................................327 8.8 NO_DATA_FOUND: Multipurpose Exception............................................................................327 ...........................................................................................................................................................................329 8.9 Exception Handler as IF Statement................................................................................................329 ...........................................................................................................................................................................331 8.10 RAISE Nothing but Exceptions...................................................................................................331 ...........................................................................................................................................................................334 9. Records in PL/SQL.....................................................................................................................................335 9.1 Record Basics.................................................................................................................................335 9.1.1 Different Types of Records............................................................................................335 9.1.2 Accessing RecordBased Data......................................................................................336 9.1.3 Benefits of Using Records.............................................................................................336 9.1.4 Guidelines for Using Records........................................................................................337 9.1.5 Referencing a Record and its Fields..............................................................................338 9.1.6 Comparing Two Records...............................................................................................338 ...........................................................................................................................................................................340 9.2 TableBased Records....................................................................................................................340 9.2.1 Declaring Records with the %ROWTYPE Attribute....................................................340 ...........................................................................................................................................................................342 9.3 CursorBased Records..................................................................................................................342 9.3.1 Choosing Columns for a Cursor Record........................................................................342 9.3.2 Setting the Record's Column Names.............................................................................343 ...........................................................................................................................................................................345 9.4 ProgrammerDefined Records......................................................................................................345 9.4.1 Declaring ProgrammerDefined Record TYPEs..........................................................345 9.4.2 Declaring the Record.....................................................................................................346 9.4.3 Examples of ProgrammerDefined Record Declarations.............................................347 ...........................................................................................................................................................................349 9.5 Assigning Values to and from Records.........................................................................................349 9.5.1 Direct Field Assignment................................................................................................349 9.5.2 SELECT INTO from an Implicit Cursor.......................................................................350 9.5.3 FETCH INTO from an Explicit Cursor.........................................................................350 9.5.4 Aggregate Assignment...................................................................................................351 ...........................................................................................................................................................................352 9.6 Record Types and Record Compatibility.......................................................................................352 9.6.1 Assignment Restrictions................................................................................................353 9.6.2 Record Initialization......................................................................................................353 ...........................................................................................................................................................................355 [Appendix A] What's on the Companion Disk? x

12. Table of Contents 9.7 Nested Records..............................................................................................................................355 9.7.1 Example of Nested Records...........................................................................................355 9.7.2 Dot Notation with Nested Records................................................................................356 9.7.3 Aggregate Assignments of Nested Records...................................................................356 9.7.4 Denormalizing Program Data with Nested Records......................................................357 10.1 PL/SQL Tables and Other Collections........................................................................................360 10.1.1 PL/SQL Tables............................................................................................................361 10.1.2 Nested Tables and VARRAYs....................................................................................362 ...........................................................................................................................................................................362 10. PL/SQL Tables..........................................................................................................................................362 ...........................................................................................................................................................................363 10.2 Characteristics of PL/SQL Tables...............................................................................................363 ...........................................................................................................................................................................365 10.3 PL/SQL Tables and DML Statements.........................................................................................365 ...........................................................................................................................................................................366 10.4 Declaring a PL/SQL Table...........................................................................................................366 10.4.1 Defining the Table TYPE............................................................................................366 10.4.2 Declaring the PL/SQL Table.......................................................................................367 ...........................................................................................................................................................................368 10.5 Referencing and Modifying PL/SQL Table Rows.......................................................................368 10.5.1 Automatic Conversion of Row Number Expressions..................................................368 10.5.2 Referencing an Undefined Row...................................................................................368 10.5.3 Nonsequential Use of PL/SQL Table..........................................................................369 10.5.4 Passing PL/SQL Tables as Parameters........................................................................370 ...........................................................................................................................................................................372 10.6 Filling the Rows of a PL/SQL Table...........................................................................................372 10.6.1 Direct Assignment.......................................................................................................372 10.6.2 Iterative Assignment....................................................................................................372 10.6.3 Aggregate Assignment.................................................................................................373 ...........................................................................................................................................................................374 10.7 Clearing the PL/SQL Table.........................................................................................................374 ...........................................................................................................................................................................376 10.8 PL/SQL Table Enhancements in PL/SQL Release 2.3................................................................376 10.8.1 PL/SQL Tables of Records..........................................................................................377 10.8.2 PL/SQL Table Builtins..............................................................................................379 ...........................................................................................................................................................................383 10.9 Working with PL/SQL Tables.....................................................................................................383 10.9.1 Transferring Database Information to PL/SQL Tables................................................383 10.9.2 DataSmart Row Numbers in PL/SQL Tables............................................................384 10.9.3 Displaying a PL/SQL Table.........................................................................................386 10.9.4 Building Traditional Arrays with PL/SQL Tables.......................................................391 10.9.5 Optimizing Foreign Key Lookups with PL/SQL Tables.............................................397 ...........................................................................................................................................................................404 11. Character Functions.................................................................................................................................405 11.1 Character Function Descriptions..................................................................................................406 11.1.1 The ASCII function.....................................................................................................406 11.1.2 The CHR function........................................................................................................406 11.1.3 The CONCAT function...............................................................................................407 11.1.4 The INITCAP function................................................................................................408 11.1.5 The INSTR function....................................................................................................409 [Appendix A] What's on the Companion Disk? xi

13. Table of Contents 11. Character Functions 11.1.6 The LENGTH function................................................................................................412 11.1.7 The LOWER function..................................................................................................412 11.1.8 The LPAD function.....................................................................................................413 11.1.9 The LTRIM function...................................................................................................414 11.1.10 The REPLACE function............................................................................................415 11.1.11 The RPAD function...................................................................................................418 11.1.12 The RTRIM function.................................................................................................419 11.1.13 The SOUNDEX function...........................................................................................420 11.1.14 The SUBSTR function...............................................................................................420 11.1.15 The TRANSLATE function.......................................................................................424 11.1.16 The UPPER function.................................................................................................425 ...........................................................................................................................................................................426 11.2 Character Function Examples......................................................................................................426 11.2.1 Parsing a Name............................................................................................................426 11.2.2 Implementing Word Wrap for Long Text....................................................................431 11.2.3 Filling Text to Fit a Line..............................................................................................434 11.2.4 Counting Substring Occurrences in Strings.................................................................436 11.2.5 Verifying String Formats with TRANSLATE.............................................................438 ...........................................................................................................................................................................441 12. Date Functions...........................................................................................................................................442 12.1 Date Function Descriptions..........................................................................................................443 12.1.1 The ADD_MONTHS function....................................................................................443 12.1.2 The LAST_DAY function...........................................................................................444 12.1.3 The MONTHS_BETWEEN function..........................................................................445 12.1.4 The NEW_TIME function...........................................................................................446 12.1.5 The NEXT_DAY function...........................................................................................447 12.1.6 The ROUND function..................................................................................................448 12.1.7 The SYSDATE function..............................................................................................450 12.1.8 The TRUNC function..................................................................................................450 ...........................................................................................................................................................................453 12.2 Date Function Examples..............................................................................................................453 12.2.1 Customizing the Behavior of ADD_MONTHS...........................................................453 12.2.2 Using NEW_TIME in ClientServer Environments...................................................454 ...........................................................................................................................................................................459 13. Numeric, LOB, and Miscellaneous Functions........................................................................................460 13.1 Numeric Function Descriptions...................................................................................................461 13.1.1 The ABS function........................................................................................................461 13.1.2 The ACOS function.....................................................................................................462 13.1.3 The ASIN function.......................................................................................................462 13.1.4 The ATAN function.....................................................................................................462 13.1.5 The ATAN2 function...................................................................................................462 13.1.6 The CEIL function.......................................................................................................463 13.1.7 The COS function........................................................................................................464 13.1.8 The COSH function.....................................................................................................464 13.1.9 The EXP function........................................................................................................464 13.1.10 The FLOOR function.................................................................................................464 13.1.11 The LN function.........................................................................................................465 13.1.12 The LOG function......................................................................................................465 13.1.13 The MOD function.....................................................................................................465 [Appendix A] What's on the Companion Disk? xii

14. Table of Contents 13. Numeric, LOB, and Miscellaneous Functions 13.1.14 The POWER function................................................................................................465 13.1.15 The ROUND function................................................................................................466 13.1.16 The SIGN function.....................................................................................................466 13.1.17 The SIN function.......................................................................................................466 13.1.18 The SINH function.....................................................................................................467 13.1.19 The SQRT function....................................................................................................467 13.1.20 The TAN function......................................................................................................467 13.1.21 The TANH function...................................................................................................467 13.1.22 The TRUNC function................................................................................................467 13.1.23 Rounding and Truncation with PL/SQL....................................................................468 ...........................................................................................................................................................................469 13.2 LOB Function Descriptions.........................................................................................................469 13.2.1 The BFILENAME function.........................................................................................469 13.2.2 The EMPTY_BLOB function......................................................................................471 13.2.3 The EMPTY_CLOB function......................................................................................471 ...........................................................................................................................................................................472 13.3 Miscellaneous Function Descriptions..........................................................................................472 13.3.1 The DUMP function....................................................................................................472 13.3.2 The GREATEST function...........................................................................................473 13.3.3 The LEAST function...................................................................................................473 13.3.4 The NVL function........................................................................................................473 13.3.5 The SQLCODE function.............................................................................................475 13.3.6 The SQLERRM function.............................................................................................475 13.3.7 The UID function.........................................................................................................476 13.3.8 The USER function......................................................................................................476 13.3.9 The USERENV function.............................................................................................477 13.3.10 The VSIZE function...................................................................................................478 ...........................................................................................................................................................................479 14. Conversion Functions...............................................................................................................................480 14.1 Conversion Formats.....................................................................................................................480 14.1.1 Date Format Models....................................................................................................481 14.1.2 Number Format Models...............................................................................................483 ...........................................................................................................................................................................486 14.2 Conversion Function Descriptions...............................................................................................486 14.2.1 The CHARTOROWID function..................................................................................486 14.2.2 The CONVERT function.............................................................................................486 14.2.3 The HEXTORAW function.........................................................................................486 14.2.4 The RAWTOHEX function.........................................................................................487 14.2.5 The ROWIDTOCHAR function..................................................................................487 14.2.6 The TO_CHAR function (date conversion).................................................................487 14.2.7 The TO_CHAR function (number conversion)...........................................................488 14.2.8 The TO_DATE function..............................................................................................488 14.2.9 The TO_NUMBER function.......................................................................................490 ...........................................................................................................................................................................491 14.3 Conversion Function Examples...................................................................................................491 14.3.1 FM: Suppressing Blanks and Zeros.............................................................................491 14.3.2 FX: Matching Formats Exactly....................................................