Tài liệu Oracle PL/SQL by Example- P1 docx

Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
Oracle
®
PL/SQL
™
by Example
FOURTH EDITION
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
This page intentionally left blank
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
Oracle
®
PL/SQL
™
by Example
FOURTH EDITION
BENJAMIN ROSENZWEIG
ELENA SILVESTROVA RAKHIMOV
Upper Saddle River, NJ • Boston • Indianapolis • San Francisco • New York •
Toronto • Montreal • London • Munich • Paris • Madrid • Cape Town • Sydney •
Tokyo • Singapore • Mexico City
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
Many of the designations used by manufacturers and sellers to distinguish their products are claimed as
trademarks. Where those designations appear in this book, and the publisher was aware of a trademark
claim, the designations have been printed with initial capital letters or in all capitals.
The authors and publisher have taken care in the preparation of this book, but make no expressed or
implied warranty of any kind and assume no responsibility for errors or omissions. No liability is
assumed for incidental or consequential damages in connection with or arising out of the use of the
information or programs contained herein.
The publisher offers excellent discounts on this book when ordered in quantity for bulk purchases or
special sales, which may include electronic versions and/or custom covers and content particular to your

business, training goals, marketing focus, and branding interests. For more information, please contact:
U.S. Corporate and Government Sales
800-382-3419

For sales outside the United States, please contact:
International Sales

Visit us on the Web: www.informit.com/ph
Library of Congress Cataloging-in-Publication Data
Rosenzweig, Benjamin.
Oracle PL/SQL by example / Benjamin Rosenzweig, Elena Silvestrova Rakhimov.
p. cm.
ISBN 0-13-714422-9 (pbk. : alk. paper) 1. PL/SQL (Computer program language) 2. Oracle
(Computer file) 3. Relational databases. I. Rakhimov, Elena Silvestrova. II. Title.
QA76.73.P258R68 2008
005.75’6—dc22
2008022398
Copyright © 2009 Pearson Education, Inc. All rights reserved. Printed in the United States of America.
This publication is protected by copyright, and permission must be obtained from the publisher prior to
any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means,
electronic, mechanical, photocopying, recording, or likewise.
For information regarding permissions, write to:
Pearson Education, Inc.
Rights and Contracts Department
501 Boylston Street, Suite 900
Boston, MA 02116
Fax: (617) 671 3447
ISBN-13: 978-0-137-14422-8
ISBN-10: 0-137-14422-9
Text printed in the United States on recycled paper at Edwards Brothers in Ann Arbor, Michigan

First printing August 2008
Editor-in-Chief: Mark Taub
Acquisitions Editor: Trina MacDonald
Development Editor: Songlin Qiu
Managing Editor: Kristy Hart
Project Editor: Todd Taber
Copy Editor: Gayle Johnson
Indexer: Erika Millen
Proofreader: Debbie Williams
Technical Reviewers: Oleg Voskoboynikov,
Shahdad Moradi
Publishing Coordinator: Olivia Basegio
Cover Designer: Chuti Prasertsith
Composition: Nonie Ratcliff
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
To my parents, Rosie and Sandy Rosenzweig, for their
love and support. —Benjamin Rosenzweig
To Sean. —Elena Silvestrova Rakhimov
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
This page intentionally left blank
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
Acknowledgments xiv
About the Authors xv
Introduction xvii
CHAPTER 1
PL/SQL Concepts 1
LAB 1.1
PL/SQL in Client/Server Architecture 2
1.1.1 Use PL/SQL Anonymous Blocks 8
1.1.2 Understand How PL/SQL Gets Executed 10

LAB 1.2
PL/SQL in SQL*Plus 12
1.2.1 Use Substitution Variables 16
1.2.2 Use the DBMS_OUTPUT.PUT_LINE Statement 17
Chapter 1 Try It Yourself 19
CHAPTER 2
General Programming Language
Fundamentals 21
LAB 2.1
PL/SQL Programming Fundamentals 22
2.1.1 Make Use of PL/SQL Language Components 23
2.1.2 Make Use of PL/SQL Variables 24
2.1.3 Handle PL/SQL Reserved Words 26
2.1.4 Make Use of Identifiers in PL/SQL 27
2.1.5 Make Use of Anchored Datatypes 28
2.1.6 Declare and Initialize Variables 31
2.1.7 Understand the Scope of a Block, Nested Blocks, and Labels 34
Chapter 2 Try It Yourself 37
CHAPTER 3
SQL in PL/SQL 39
LAB 3.1
Making Use of DML in PL/SQL 40
3.1.1 Use the Select INTO Syntax for Variable Initialization 41
3.1.2 Use DML in a PL/SQL Block 42
3.1.3 Make Use of a Sequence in a PL/SQL Block 44
LAB 3.2
Making Use of SAVEPOINT 45
3.2.1 Make Use of COMMIT, ROLLBACK, and SAVEPOINT
in a PL/SQL Block 48
Chapter 3 Try It Yourself 51

Contents
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
CHAPTER 4
Conditional Control: IF Statements 53
LAB 4.1
IF Statements 54
4.1.1 Use the IF-THEN Statement 58
4.1.2 Use the IF-THEN-ELSE Statement 62
LAB 4.2
ELSIF Statements 65
4.2.1 Use the ELSIF Statement 69
LAB 4.3
Nested IF Statements 74
4.3.1 Use Nested IF Statements 76
Chapter 4 Try It Yourself 80
CHAPTER 5
Conditional Control: CASE Statements 81
LAB 5.1
CASE Statements 82
5.1.1 Use the CASE Statement 89
5.1.2 Use the Searched CASE Statement 91
LAB 5.2
CASE Expressions 96
5.2.1 Use the CASE Expression 100
LAB 5.3
NULLIF and COALESCE Functions 103
5.3.1 The NULLIF Function 107
5.3.2 Use the COALESCE Function 109
Chapter 5 Try It Yourself 112
CHAPTER 6

Iterative Control: Part I 113
LAB 6.1
Simple Loops 114
6.1.1 Use Simple Loops with EXIT Conditions 118
6.1.2 Use Simple Loops with EXIT WHEN Conditions 120
LAB 6.2
WHILE Loops 124
6.2.1 Use WHILE Loops 128
LAB 6.3
Numeric FOR Loops 132
6.3.1 Use Numeric FOR Loops with the IN Option 137
6.3.2 Use Numeric FOR Loops with the REVERSE Option 139
Chapter 6 Try It Yourself 142
CHAPTER 7
Iterative Control: Part II 143
LAB 7.1
The CONTINUE Statement 144
7.1.1 Use the CONTINUE Statement 146
7.1.2 Use the CONTINUE WHEN Condition 152
viii
Contents
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
LAB 7.2
Nested Loops 154
7.2.1 Use Nested Loops 157
Chapter 7 Try It Yourself 161
CHAPTER 8
Error Handling and Built-in Exceptions 163
LAB 8.1
Handling Errors 164

8.1.1 Understand the Importance of Error Handling 167
LAB 8.2
Built-in Exceptions 169
8.2.1 Use Built-in Exceptions 174
Chapter 8 Try It Yourself 178
CHAPTER 9
Exceptions 179
LAB 9.1
Exception Scope 180
9.1.1 Understand the Scope of an Exception 183
LAB 9.2
User-Defined Exceptions 188
9.2.1 Use User-Defined Exceptions 193
LAB 9.3
Exception Propagation 197
9.3.1 Understand How Exceptions Propagate 203
9.3.2 Reraise Exceptions 206
Chapter 9 Try It Yourself 209
CHAPTER 10
Exceptions: Advanced Concepts 211
LAB 10.1
RAISE_APPLICATION_ERROR 212
10.1.1 Use RAISE_APPLICATION_ERROR 215
LAB 10.2
EXCEPTION_INIT Pragma 217
10.2.1 USE the EXCEPTION_INIT Pragma 219
LAB 10.3
SQLCODE and SQLERRM 222
10.3.1 Use SQLCODE and SQLERRM 225
Chapter 10 Try It Yourself 227

CHAPTER 11
Introduction to Cursors 229
LAB 11.1
Cursor Manipulation 230
11.1.1 Make Use of Record Types 234
11.1.2 Process an Explicit Cursor 235
11.1.3 Make Use of Cursor Attributes 240
11.1.4 Put It All Together 242
Contents
ix
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
LAB 11.2
Using Cursor FOR Loops and Nested Cursors 246
11.2.1 Use a Cursor FOR Loop 247
11.2.2 Process Nested Cursors 247
Chapter 11 Try It Yourself 252
CHAPTER 12
Advanced Cursors 253
LAB 12.1
Using Parameters with Cursors and Complex Nested Cursors 254
12.1.1 Use Parameters in a Cursor 255
12.1.2 Use Complex Nested Cursors 255
LAB 12.2
FOR UPDATE and WHERE CURRENT Cursors 258
12.2.1 For UPDATE and WHERE CURRENT Cursors 258
CHAPTER 13
Triggers 263
LAB 13.1
What Triggers Are 264
13.1.1 Understand What a Trigger Is 272

13.1.2 Use BEFORE and AFTER Triggers 274
LAB 13.2
Types of Triggers 277
13.2.1 Use Row and Statement Triggers 283
13.2.2 Use INSTEAD OF Triggers 285
Chaper 13 Try It Yourself 290
CHAPTER 14
Compound Triggers 291
LAB 14.1
Mutating Table Issues 292
14.1.1 Understand Mutating Tables 296
LAB 14.2
Compound Triggers 300
14.2.1 Understand Compound Triggers 306
Chapter 14 Try It Yourself 313
CHAPTER 15
Collections 315
LAB 15.1
PL/SQL Tables 316
15.1.1 Use Associative Arrays 326
15.1.2 Use Nested Tables 330
LAB 15.2
Varrays 334
15.2.1 Use Varrays 338
LAB 15.3
Multilevel Collections 342
15.3.1 Use Multilevel Collections 344
Chapter 15 Try It Yourself 348
x
Contents

Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
CHAPTER 16
Records 349
LAB 16.1
Record Types 350
16.1.1 Use Table-Based and Cursor-Based Records 358
16.1.2 Use User-Defined Records 362
LAB 16.2
Nested Records 367
16.2.1 Use Nested Records 369
LAB 16.3
Collections of Records 373
16.3.1 Use Collections of Records 374
Chapter 16 Try It Yourself 378
CHAPTER 17
Native Dynamic SQL 379
LAB 17.1
EXECUTE IMMEDIATE Statements 380
17.1.1 Use the EXECUTE IMMEDIATE Statement 387
LAB 17.2
OPEN-FOR, FETCH, and CLOSE Statements 392
17.2.1 Use OPEN-FOR, FETCH, and CLOSE Statements 395
Chapter 17 Try It Yourself 401
CHAPTER 18
Bulk SQL 403
LAB 18.1
The FORALL Statement 404
18.1.1 Use the FORALL Statement 413
LAB 18.2
The BULK COLLECT Clause 422

18.2.1 Use the BULK COLLECT Statement 428
Chapter 18 Try It Yourself 437
CHAPTER 19
Procedures 439
LAB 19.1
Creating Procedures 441
19.1.1 Create Procedures 441
19.1.2 Query the Data Dictionary for Information on Procedures 443
LAB 19.2
Passing Parameters into and out of Procedures 444
19.2.1 Use IN and OUT Parameters with Procedures 445
Chapter 19 Try It Yourself 447
Part 1 447
Part 2 447
Contents
xi
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
CHAPTER 20
Functions 449
LAB 20.1
Creating and Using Functions 450
20.1.1 Create Stored Functions 451
20.1.2 Make Use of Functions 452
20.1.3 Invoke Functions in SQL Statements 453
20.1.4 Write Complex Functions 454
Chapter 20 Try It Yourself 455
CHAPTER 21
Packages 457
LAB 21.1
The Benefits of Using Packages 458

21.1.1 Create Package Specifications 460
21.1.2 Create Package Bodies 462
21.1.3 Call Stored Packages 464
21.1.4 Create Private Objects 465
21.1.5 Create Package Variables and Cursors 469
LAB 21.2
Cursor Variables 471
21.2.1 Make Use of Cursor Variables 475
LAB 21.3
Extending the Package 480
21.3.1 Extend the Package 480
Chapter 21 Try It Yourself 493
CHAPTER 22
Stored Code 495
LAB 22.1
Gathering Information About Stored Code 496
22.1.1 Get Stored Code Information from the Data Dictionary 496
22.1.2 Enforce the Purity Level with the RESTRICT_REFERENCES
Pragma 500
22.1.3 Overload Modules 506
Chapter 22 Try It Yourself 512
CHAPTER 23
Object Types in Oracle 513
LAB 23.1
Object Types 514
23.1.1 Use Object Types 522
23.1.2 Use Object Types with Collections 526
LAB 23.2
Object Type Methods 531
23.2.1 Use Object Type Methods 544

Chapter 23 Try It Yourself 554
xii
Contents
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
CHAPTER 24
Oracle Supplied Packages 555
LAB 24.1
Making Use of Oracle Supplied Packages to Profile PL/SQL, Access Files,
and Schedule Jobs 556
24.1.1 Access Files with UTL_FILE 563
24.1.2 Schedule Jobs with DBMS_JOB 563
24.1.3 Submit Jobs 564
LAB 24.2
Making Use of Oracle-Supplied Packages to Generate an Explain
Plan and Create HTML Pages 568
24.2.1 Generate an Explain Plan with DBMS_XPLAN 572
LAB 24.3
Creating Web Pages with the Oracle Web Toolkit 578
24.3.1 Create an HTML Page with the Oracle Web Toolkit 594
APPENDIX A
PL/SQL Formatting Guide 597
APPENDIX B
Student Database Schema 601
APPENDIX C
ANSI SQL Standards 607
APPENDIX D
Answers to the Try It Yourself Sections 613
INDEX
705
1) Visit www.informit.com/title/0137144229 to learn how to register this product and gain

access to additional content.
2) To register this product and gain access to bonus content, go to www.informit.com/register to
sign in and enter the ISBN. After you register the product, a link to the additional content will
be listed on your Account page, under Registered Products.
Contents
xiii
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
ACKNOWLEDGMENTS
Benjamin Rosenzweig: I would like to thank my coauthor, Elena Silvestrova Rakhimov, for
being a wonderful and knowledgeable colleague to work with. I would also like to thank
Douglas Scherer for giving me the opportunity to work on this book, as well as for providing
constant support and assistance through the entire writing process. I am indebted to the team at
Prentice Hall, which includes Trina MacDonald, Songlin Qiu, Todd Taber, Shahdad Moradi, and
Oleg Voskoboynikov. Their contributions, suggestions, and edits helped improve our original
manuscript and make the book what it is today. Finally, I would like to thank my many friends
and family, especially Edward Clarin and Edward Knopping, for helping me through the long
process of putting the whole book together, which included many late nights and weekends.
Elena Silvestrova Rakhimov: My contribution to this book reflects the help and advice of many
people. I am particularly indebted to my coauthor, Benjamin Rosenzweig, for making this project
a rewarding and enjoyable experience. Special thanks to Trina MacDonald, Songlin Qiu, Todd
Taber, and many others at Prentice Hall who diligently worked to bring this book to market.
Thanks to Shahdad Moradi and Oleg Voskoboynikov for their valuable comments and sugges-
tions. Most importantly, to my family, whose excitement, enthusiasm, inspiration, and support
encouraged me to work hard to the very end, and were exceeded only by their love.
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
ABOUT THE AUTHORS
Benjamin Rosenzweig is a software development manager at Misys Treasury & Capital Markets,
where he has worked since 2002. Prior to that he was a principal consultant for more than three
years at Oracle Corporation in the Custom Development Department. His computer experience
ranges from creating an electronic Tibetan–English dictionary in Kathmandu, Nepal, to supporting

presentation centers at Goldman Sachs and managing a trading system at TIAA-CREF. Rosenzweig
has been an instructor at the Columbia University Computer Technology and Application program
in New York City since 1998. In 2002 he was awarded the Outstanding Teaching Award from the
chair and director of the CTA program. He holds a B.A. from Reed College and a certificate in data-
base development and design from Columbia University. His previous books with Prentice Hall are
Oracle Forms Developer: The Complete Video Course (ISBN: 0-13-032124-9) and Oracle Web
Application Programming for PL/SQL Developers (ISBN: 0-13-047731-1).
Elena Silvestrova Rakhimov has more than 15 years of experience in database development
in a wide spectrum of enterprise and business environments, ranging from nonprofit organiza-
tions to Wall Street. She currently works at Alea Software, where she serves as Senior Developer
and Team Lead. Her determination to stay hands-on notwithstanding, Rakhimov has managed
to excel in the academic arena, having taught relational database programming at Columbia
University’s highly esteemed Computer Technology and Applications program. She was educated
in database analysis and design at Columbia University and in applied mathematics at Baku State
University in Azerbaijan. She currently resides in Vancouver, Canada.
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
This page intentionally left blank
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
INTRODUCTION
PL/SQL New Features in Oracle 11g
Oracle 11g has introduced a number of new features and improvements for PL/SQL. This intro-
duction briefly describes features not covered in this book and points you to specific chapters
for features that are within scope of this book. The list of features described here is also available
in the “What’s New in PL/SQL?” section of the PL/SQL Language Reference manual offered as
part of Oracle help available online.
The new PL/SQL features and enhancements are as follows:
.
Enhancements to regular expression built-in SQL functions
.
SIMPLE_INTEGER, SIMPLE_FLOAT, and SIMPLE_DOUBLE datatypes

.
CONTINUE statement
.
Sequences in PL/SQL expressions
.
Dynamic SQL enhancements
.
Named and mixed notation in PL/SQL subprogram invocations
.
Cross-session PL/SQL function result cache
.
More control over triggers
.
Compound triggers
.
Database resident connection pool
.
Automatic subprogram inlining
.
PL/Scope
.
PL/SQL hierarchical profiler
.
PL/SQL native compiler generates native code directly
Enhancements to Regular Expression Built-In SQL Functions
In this release Oracle has introduced a new regular expression built-in function,
REGEXP_COUNT. It returns the number of times a specified search pattern appears in a
source string.
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
FOR EXAMPLE

SELECT
REGEXP_COUNT ('Oracle PL/SQL By Example Updated for Oracle 11g',
'ora', 1, 'i')
FROM dual;
REGEXP_COUNT('ORACLEPL/SQLBYEXAMPLEUPDATEDFORORACLE11G','ORA',1,'I')
--------------------------------------------------------------------
2
The REGEXP_COUNT function returns how many times the search pattern
'ora'
appears in
the source string
'Oracle PL/SQL...'1
indicates the position of the source string where the
search begins, and
'i'
indicates case-insensitive matching.
The existing regular expression built-in functions, REGEXP_INSTR and REGEXP_SUBSTR, have
a new parameter called SUBEXPR. This parameter represents a subexpression in a search pattern.
Essentially it is a portion of a search pattern enclosed in parentheses that restricts pattern
matching, as illustrated in the following example.
FOR EXAMPLE
SELECT
REGEXP_INSTR ('Oracle PL/SQL By Example Updated for Oracle 11g',
'((ora)(cle))', 1, 2, 0, 'i')
FROM dual;
REGEXP_INSTR('ORACLEPL/SQLBYEXAMPLEUPDATEDFORORACLE11G',...)
------------------------------------------------------------
38
The REGEXP_INSTR function returns the position of the first character in the source string
'Oracle PL/SQL…'

corresponding to the second occurrence of the first subexpression
'ora'
in the seach pattern
(ora)(cle)
.
1
indicates the position of the source string where the search
begins,
2
indicates the occurrence of the subexpression in the source string,
0
indicates that the
position returned corresponds to the position of the first character where the match occurs, and
'i'
indicates case-insensitive matching and REGEXP_SUBSTR.
SIMPLE_INTEGER, SIMPLE_FLOAT, and SIMPLE_DOUBLE
Datatypes
These datatypes are predefined subtypes of the PLS_INTEGER, BINARY_FLOAT, and
BINARY_DOUBLE, respectively. As such, they have the same range as their respective base types.
In addition, these subtypes have NOT NULL constraints.
xviii
Introduction
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.
These subtypes provide significant performance improvements over their respective base types
when the PLSQL_CODE_TYPE parameter is set to NATIVE. This is because arithmetic opera-
tions for these subtypes are done directly in the hardware layer. Note that when
PLSQL_CODE_TYPE is set to INTERPRETED (the default value), the performance gains are
significantly smaller. This is illustrated by the following example.
FOR EXAMPLE
SET SERVEROUTPUT ON

DECLARE
v_pls_value1 PLS_INTEGER := 0;
v_pls_value2 PLS_INTEGER := 1;
v_simple_value1 SIMPLE_INTEGER := 0;
v_simple_value2 SIMPLE_INTEGER := 1;
-- Following are used for elapsed time calculation
-- The time is calculated in 100th of a second
v_start_time NUMBER;
v_end_time NUMBER;
BEGIN
-- Perform calculations with PLS_INTEGER
v_start_time := DBMS_UTILITY.GET_TIME;
FOR i in 1..50000000 LOOP
v_pls_value1 := v_pls_value1 + v_pls_value2;
END LOOP;
v_end_time := DBMS_UTILITY.GET_TIME;
DBMS_OUTPUT.PUT_LINE ('Elapsed time for PLS_INTEGER: '||
(v_end_time - v_start_time));
-- Perform the same calculations with SIMPLE_INTEGER
v_start_time := DBMS_UTILITY.GET_TIME;
FOR i in 1..50000000 LOOP
v_simple_value1 := v_simple_value1 + v_simple_value2;
END LOOP;
v_end_time := DBMS_UTILITY.GET_TIME;
DBMS_OUTPUT.PUT_LINE ('Elapsed time for SIMPLE_INTEGER: '||
(v_end_time - v_start_time));
END;
Introduction
xix
Please purchase PDF Split-Merge on www.verypdf.com to remove this watermark.