sams teach yourself sql in 10 minutes -...
TRANSCRIPT
in 10 Minutes
SQLSamsTeachYourself
Ben Forta
800 East 96th Street, Indianapolis, Indiana 46240
Fourth Edition
Sams Teach Yourself SQL in 10 Minutes, Fourth EditionCopyright © 2013 by Pearson Education, Inc.
All rights reserved. No part of this book shall be reproduced,stored in a retrieval system, or transmitted by any means, elec-tronic, mechanical, photocopying, recording, or otherwise, withoutwritten permission from the publisher. No patent liability isassumed with respect to the use of the information containedherein. Although every precaution has been taken in the prepara-tion of this book, the publisher and author assume no responsibil-ity for errors or omissions. Nor is any liability assumed for dam-ages resulting from the use of the information contained herein.
ISBN-13: 9780672336072
ISBN-10: 0672336073
Library of Congress cataloging-in-Publication Data is on file.
Printed in the United States of America
Second Printing: July 2013
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Table of Contents
Introduction 1Who Is the Teach Yourself SQL Book For?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
DBMSs Covered in This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Conventions Used in This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1 Understanding SQL 5Database Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
What Is SQL? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Try It Yourself . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2 Retrieving Data 13The SELECT Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Retrieving Individual Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Retrieving Multiple Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Retrieving All Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Retrieving Distinct Rows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Limiting Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Using Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 Sorting Retrieved Data 27Sorting Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Sorting by Multiple Columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Sorting by Column Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Specifying Sort Direction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4 Filtering Data 35Using the WHERE Clause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
The WHERE Clause Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5 Advanced Data Filtering 43Combining WHERE Clauses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Using the IN Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Using the NOT Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
6 Using Wildcard Filtering 53Using the LIKE Operator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Tips for Using Wildcards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
7 Creating Calculated Fields 61Understanding Calculated Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Concatenating Fields. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Performing Mathematical Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
8 Using Data Manipulation Functions 71Understanding Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Using Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
9 Summarizing Data 81Using Aggregate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Aggregates on Distinct Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Combining Aggregate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
iv Sams Teach Yourself SQL in 10 Minutes
10 Grouping Data 93Understanding Data Grouping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Creating Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Filtering Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
Grouping and Sorting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SELECT Clause Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
11 Working with Subqueries 103Understanding Subqueries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Filtering by Subquery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Using Subqueries as Calculated Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
12 Joining Tables 113Understanding Joins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Creating a Join . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
13 Creating Advanced Joins 125Using Table Aliases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
Using Different Join Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Using Joins with Aggregate Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Using Joins and Join Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
14 Combining Queries 137Understanding Combined Queries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Creating Combined Queries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
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15 Inserting Data 145Understanding Data Insertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Copying from One Table to Another . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
16 Updating and Deleting Data 155Updating Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Deleting Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
Guidelines for Updating and Deleting Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
17 Creating and Manipulating Tables 163Creating Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Updating Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Deleting Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
Renaming Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
18 Using Views 175Understanding Views. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Creating Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
19 Working with Stored Procedures 187Understanding Stored Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Why to Use Stored Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Executing Stored Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Creating Stored Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
20 Managing Transaction Processing 197Understanding Transaction Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197
Controlling Transactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
vi Sams Teach Yourself SQL in 10 Minutes
21 Using Cursors 205Understanding Cursors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205
Working with Cursors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
22 Understanding Advanced SQL Features 213Understanding Constraints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
Understanding Indexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Understanding Triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Database Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
A Sample Table Scripts 225Understanding the Sample Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225
Obtaining the Sample Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
B Working in Popular Applications 233Using Apache Open Office Base. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233
Using Adobe ColdFusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Using IBM DB2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Using MariaDB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Using Microsoft Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Using Microsoft ASP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Using Microsoft ASP.NET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237
Using Microsoft Query . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238
Using Microsoft SQL Server (including Microsoft SQL ServerExpress) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
Using MySQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Using Oracle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Using Oracle Express . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Using PHP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242
Using PostgreSQL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243
Using SQLite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
Configuring ODBC Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245
viiTable of Contents
C SQL Statement Syntax 247ALTER TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
COMMIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
CREATE INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
CREATE PROCEDURE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
CREATE TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
CREATE VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
DELETE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
DROP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
INSERT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
INSERT SELECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
ROLLBACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
SELECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
UPDATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252
D Using SQL Datatypes 253String Datatypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
Numeric Datatypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
Date and Time Datatypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
Binary Datatypes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258
E SQL Reserved Words 259
Index 265
viii Sams Teach Yourself SQL in 10 Minutes
About the Author
Ben Forta is Adobe Systems’ Director of Developer Relations and hasmore than 20 years of experience in the computer industry in productdevelopment, support, training, and product marketing. He is the author ofthe best-selling Sams Teach Yourself SQL in 10 Minutes, spinoff titles onMySQL and SQL Server T-SQL, ColdFusion Web ApplicationConstruction Kit and Advanced ColdFusion Application Development(both published by Adobe Press), Sams Teach Yourself RegularExpressions in 10 Minutes, as well as books on Flash, Java, Windows, andother subjects. He has extensive experience in database design and devel-opment, has implemented databases for several highly successful com-mercial software programs and websites, and is a frequent lecturer andcolumnist on Internet and database technologies. Ben lives in Oak Park,Michigan, with his wife Marcy and their seven children. Ben welcomesyour e-mail at [email protected] and invites you to visit his website athttp://forta.com/.
Acknowledgments
Thanks to the team at Sams for all these years of support, dedication, andencouragement. A special thank-you to Mark Taber for encouraging thislong awaited update and for suggesting and facilitating the code coloring,which significantly enhances the readability and value of this new edition.
Thanks to my colleague Greg Wilson for his thorough technical review.
Thanks to the many hundreds of you who provided feedback on the firstthree editions of this book. Fortunately, most of it was positive, and all ofit was appreciated. The enhancements and changes in this edition are adirect response to your feedback, which I continue to welcome.
Thanks to the dozens of colleges and universities who have made thisbook part of their IT and computer science curriculums. Being includedand trusted by professors and teachers this way is immensely rewardingand equally humbling.
And finally, thanks to the more than one-quarter million of you whobought the previous editions of this book, making it not just my best-selling title, but also one of the best-selling books on the subject. Yourcontinued support is the highest compliment an author can ever be paid.
—Ben Forta
We Want to Hear from You!
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You can e-mail or write directly to let us know what you did or didn’t likeabout this book—as well as what we can do to make our books stronger.
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Introduction
SQL is the most widely used database language. Whether you are anapplication developer, database administrator, web application designer,mobile app developer, or Microsoft Office user, a good working knowl-edge of SQL is an important part of interacting with databases.
This book was born out of necessity. I had been teaching Web applicationdevelopment for several years, and students were constantly asking forSQL book recommendations. There are lots of SQL books out there.Some are actually very good. But they all have one thing in common: formost users they teach just too much information. Instead of teaching SQLitself, most books teach everything from database design and normaliza-tion to relational database theory and administrative concerns. And whilethose are all important topics, they are not of interest to most of us whojust need to learn SQL.
And so, not finding a single book that I felt comfortable recommending, Iturned that classroom experience into the book you are holding. Sams TeachYourself SQL in 10 Minutes will teach you SQL you need to know, startingwith simple data retrieval and working on to more complex topics includingthe use of joins, subqueries, stored procedures, cursors, triggers, and tableconstraints. You’ll learn methodically, systematically, and simply—inlessons that will each take 10 minutes or less to complete.
Now in its fourth edition, this book has taught SQL to over a quarter mil-lion English speaking users, and has been translated into over a dozenother languages too so as to help users the globe over. And now it is yourturn. So turn to Lesson 1, and get to work. You’ll be writing world classSQL in no time at all.
Who Is the Teach Yourself SQLBook For?This book is for you if
. You are new to SQL.
. You want to quickly learn how to get the most out of SQL.
. You want to learn how to use SQL in your own applicationdevelopment.
. You want to be productive quickly and easily in SQL withouthaving to call someone for help.
DBMSs Covered in This BookFor the most part, the SQL taught in this book will apply to any DatabaseManagement System (DBMS). However, as all SQL implementations arenot created equal, the following DBMSs are explicitly covered (and spe-cific instructions or notes are included where needed):
. Apache Open Office Base
. IBM DB2
. Microsoft Access
. Microsoft SQL Server (including Microsoft SQL ServerExpress)
. MariaDB
. MySQL
. Oracle (including Oracle Express)
. PostgreSQL
. SQLite
Example databases (or SQL scripts to create the example databases) are available for all of these DBMSs on the book webpage athttp://forta.com/books/0672336073/.
2 Sams Teach Yourself SQL in 10 Minutes
3Introduction
Conventions Used in This BookThis book uses different typefaces to differentiate between code and regu-lar English, and also to help you identify important concepts.
Text that you type and text that should appear on your screen is presentedin monospace type.
It will look like this to mimic the way text looks on yourscreen.
Placeholders for variables and expressions appear in monospace italic font. You should replace the placeholder with the specific value it represents.
This arrow (➥) at the beginning of a line of code means that a single lineof code is too long to fit on the printed page. Continue typing all the char-acters after the ➥ as though they were part of the preceding line.
NOTE:
A Note presents interesting pieces of information related to the sur-rounding discussion.
TIP:
A Tip offers advice or teaches an easier way to do something.
CAUTION:
A Caution advises you about potential problems and helps you steerclear of disaster.
PLAIN ENGLISH
New Term icons provide clear definitions of new, essential terms.
Input ▼
The Input icon identifies code that you can type in. It usually appears nextto a listing.
Output ▼
The Output icon highlights the output produced by running a program. Itusually appears after a listing.
Analysis ▼
The Analysis icon alerts you to the author’s line-by-line analysis of a program.
4 Sams Teach Yourself SQL in 10 Minutes
LESSON 2
Retrieving Data
In this lesson, you’ll learn how to use the SELECT statement to retrieveone or more columns of data from a table.
The SELECT StatementAs explained in Lesson 1, “Understanding SQL,” SQL statements aremade up of plain English terms. These terms are called keywords, andevery SQL statement is made up of one or more keywords. The SQLstatement that you’ll probably use most frequently is the SELECT state-ment. Its purpose is to retrieve information from one or more tables.
Keyword
A reserved word that is part of the SQL language. Never name atable or column using a keyword. Appendix E, “SQL ReservedWords,” lists some of the more common reserved words.
To use SELECT to retrieve table data you must, at a minimum, specify twopieces of information—what you want to select, and from where you wantto select it.
NOTE: Following Along with the Examples
The sample SQL statements (and sample output) throughout thelessons in this book use a set of data files that are described inAppendix A, “Sample Table Scripts.” If you’d like to follow along andtry the examples yourself (I strongly recommend that you do so),refer to Appendix A which contains instructions on how to downloador create these data files.
It is important to understand that SQL is a language, not an applica-tion. The way that you specify SQL statements and display state-ment output varies from one application to the next. To assist you inadapting the examples to your own environment, Appendix B,“Working in Popular Applications,” explains how to issue the state-ments taught throughout this book using many popular applicationsand development environments. And if you need an application withwhich to follow along, Appendix B has recommendations for you too.
Retrieving Individual ColumnsWe’ll start with a simple SQL SELECT statement, as follows:
Input ▼SELECT prod_nameFROM Products;
Analysis ▼
The previous statement uses the SELECT statement to retrieve a single col-umn called prod_name from the Products table. The desired columnname is specified right after the SELECT keyword, and the FROM keywordspecifies the name of the table from which to retrieve the data. The outputfrom this statement is shown in the following:
14 LESSON 2: Retrieving Data
Output ▼prod_name--------------------Fish bean bag toyBird bean bag toyRabbit bean bag toy8 inch teddy bear12 inch teddy bear18 inch teddy bearRaggedy AnnKing dollQueen doll
NOTE: Unsorted Data
If you tried this query yourself you might have discovered that thedata was displayed in a different order than shown here. If this isthe case, don’t worry—it is working exactly as it is supposed to. Ifquery results are not explicitly sorted (we’ll get to that in the nextlesson) then data will be returned in no order of any significance. Itmay be the order in which the data was added to the table, but itmay not. As long as your query returned the same number of rowsthen it is working.
A simple SELECT statement similar to the one used above returns all therows in a table. Data is not filtered (so as to retrieve a subset of theresults), nor is it sorted. We’ll discuss these topics in the next few lessons.
TIP: Terminating Statements
Multiple SQL statements must be separated by semicolons (the ;character). Most DBMSs do not require that a semicolon be specifiedafter single statements. But if your particular DBMS complains, youmight have to add it there. Of course, you can always add a semi-colon if you wish. It’ll do no harm, even if it is, in fact, not needed.
15Retrieving Individual Columns
TIP: SQL Statement and Case
It is important to note that SQL statements are case-insensitive, soSELECT is the same as select, which is the same as Select. ManySQL developers find that using uppercase for all SQL keywords andlowercase for column and table names makes code easier to readand debug. However, be aware that while the SQL language is case-insensitive, the names of tables, columns, and values may not be(that depends on your DBMS and how it is configured).
TIP: Use of White Space
All extra white space within a SQL statement is ignored when thatstatement is processed. SQL statements can be specified on onelong line or broken up over many lines. So, the following three state-ments are functionality identical:
SELECT prod_nameFROM Products;
SELECT prod_name FROM Products;
SELECTprod_nameFROMProducts;
Most SQL developers find that breaking up statements over multiplelines makes them easier to read and debug.
Retrieving Multiple ColumnsTo retrieve multiple columns from a table, the same SELECT statement isused. The only difference is that multiple column names must be specifiedafter the SELECT keyword, and each column must be separated by a comma.
TIP: Take Care with Commas
When selecting multiple columns be sure to specify a commabetween each column name, but not after the last column name.Doing so will generate an error.
16 LESSON 2: Retrieving Data
The following SELECT statement retrieves three columns from the prod-ucts table:
Input ▼SELECT prod_id, prod_name, prod_priceFROM Products;
Analysis ▼
Just as in the prior example, this statement uses the SELECT statement toretrieve data from the Products table. In this example, three columnnames are specified, each separated by a comma. The output from thisstatement is shown below:
Output ▼prod_id prod_name prod_price--------- -------------------- ----------BNBG01 Fish bean bag toy 3.4900BNBG02 Bird bean bag toy 3.4900BNBG03 Rabbit bean bag toy 3.4900BR01 8 inch teddy bear 5.9900BR02 12 inch teddy bear 8.9900BR03 18 inch teddy bear 11.9900RGAN01 Raggedy Ann 4.9900RYL01 King doll 9.4900RYL02 Queen dool 9.4900
NOTE: Presentation of Data
As you will notice in the above output, SQL statements typicallyreturn raw, unformatted data. Data formatting is a presentationissue, not a retrieval issue. Therefore, presentation (for example,displaying the above price values as currency amounts with the cor-rect number of decimal places) is typically specified in the applica-tion that displays the data. Actual retrieved data (without application-provided formatting) is rarely used.
17Retrieving Multiple Columns
18 LESSON 2: Retrieving Data
Retrieving All ColumnsIn addition to being able to specify desired columns (one or more, as seenabove), SELECT statements can also request all columns without having tolist them individually. This is done using the asterisk (*) wildcard charac-ter in lieu of actual column names, as follows:
Input ▼SELECT *FROM Products;
Analysis ▼
When a wildcard (*) is specified, all the columns in the table are returned.The column order will typically, but not always, be the physical order inwhich the columns appear in the table definition. However, SQL data is sel-dom displayed as is. (Usually, it is returned to an application that formats orpresents the data as needed). As such, this should not pose a problem.
CAUTION: Using Wildcards
As a rule, you are better off not using the * wildcard unless you real-ly do need every column in the table. Even though use of wildcardsmay save you the time and effort needed to list the desired columnsexplicitly, retrieving unnecessary columns usually slows down theperformance of your retrieval and your application.
TIP: Retrieving Unknown Columns
There is one big advantage to using wildcards. As you do not explic-itly specify column names (because the asterisk retrieves every col-umn), it is possible to retrieve columns whose names are unknown.
Retrieving Distinct RowsAs you have seen, SELECT returns all matched rows. But what if you donot want every occurrence of every value? For example, suppose you wantthe vendor ID of all vendors with products in your products table:
Input ▼SELECT vend_idFROM Products;
Output ▼vend_id----------BRS01BRS01BRS01DLL01DLL01DLL01DLL01FNG01FNG01
The SELECT statement returned 14 rows (even though there are only fourvendors in that list) because there are 14 products listed in the productstable. So how could you retrieve a list of distinct values?
The solution is to use the DISTINCT keyword which, as its name implies,instructs the database to only return distinct values.
Input ▼SELECT DISTINCT vend_idFROM Products;
19Retrieving Distinct Rows
Analysis ▼
SELECT DISTINCT vend_id tells the DBMS to only return distinct(unique) vend_id rows, and so only four rows are returned, as seen in thefollowing output. If used, the DISTINCT keyword must be placed directlyin front of the column names.
Output ▼vend_id----------BRS01DLL01FNG01
CAUTION: Can’t Be Partially DISTINCT
The DISTINCT keyword applies to all columns, not just the one itprecedes. If you were to specify SELECT DISTINCT vend_id,prod_price, all rows would be retrieved unless both of the specifiedcolumns were distinct.
Limiting ResultsSELECT statements return all matched rows, possibly every row in thespecified table. What if you want to return just the first row or a set num-ber of rows? This is doable, but unfortunately, this is one of those situa-tions where all SQL implementations are not created equal.
In Microsoft SQL Server and Microsoft Access you can use the TOP key-word to limit the top number of entries, as seen here:
Input ▼SELECT TOP 5 prod_nameFROM Products;
20 LESSON 2: Retrieving Data
Output ▼prod_name-----------------8 inch teddy bear12 inch teddy bear18 inch teddy bearFish bean bag toyBird bean bag toy
Analysis ▼
The previous statement uses the SELECT TOP 5 statement to retrieve justthe first five rows.
If you are using DB2, well, then you get to use SQL unique to thatDBMS, like this:
Input ▼SELECT prod_nameFROM ProductsFETCH FIRST 5 ROWS ONLY;
Analysis ▼
FETCH FIRST 5 ROWS ONLY does exactly what it suggests.
If you are using Oracle you need to count rows based on ROWNUM (a rownumber counter) like this:
Input ▼SELECT prod_nameFROM ProductsWHERE ROWNUM <=5;
If you are using MySQL, MariaDB, PostgreSQL, or SQLite, you can usethe LIMIT clause, as follows:
21Limiting Results
Input ▼
SELECT prod_nameFROM ProductsLIMIT 5;
Analysis ▼
The previous statement uses the SELECT statement to retrieve a single col-umn. LIMIT 5 instructs the supported DBMSs to return no more than fiverows. The output from this statement is shown in the following code.
To get the next five rows, specify both where to start and the number ofrows to retrieve, like this:
Input ▼
SELECT prod_nameFROM ProductsLIMIT 5 OFFSET 5;
Analysis ▼
LIMIT 5 OFFSET 5 instructs supported DBMSs to return five rows start-ing from row 5. The first number is the number of rows to retrieve, andthe second is where to start. The output from this statement is shown inthe following code:
Output ▼
prod_name-------------------Rabbit bean bag toyRaggedy AnnKing dollQueen doll
So, LIMIT specifies the number of rows to return. LIMIT with an OFFSETspecifies where to start from. In our example there are only nine productsin the Products table, so LIMIT 5 OFFSET 5 returned just four rows (asthere was no fifth).
22 LESSON 2: Retrieving Data
23Using Comments
CAUTION: Row 0
The first row retrieved is row 0, not row 1. As such, LIMIT 1 OFFSET1 will retrieve the second row, not the first one.
TIP: MySQL, MariaDB, and SQLite Shortcut
MySQL, MariaDB, and SQLite support a shorthand version of LIMIT4 OFFSET 3, enabling you to combine them as LIMIT 3,4. Usingthis syntax, the value before the , is the LIMIT and the value afterthe , is the OFFSET.
NOTE: Not ALL SQL Is Created Equal
I included this section on limiting results for one reason only, todemonstrate that while SQL is usually quite consistent across imple-mentations, you can’t rely on it always being so. While very basicstatements tend to be very portable, more complex ones tend to beless so. Keep that in mind as you search for SQL solutions to spe-cific problems.
Using CommentsAs you have seen, SQL statements are instructions that are processed byyour DBMS. But what if you wanted to include text that you’d not wantprocessed and executed? Why would you ever want to do this? Here are afew reasons:
. The SQL statements we’ve been using here are all very shortand very simple. But, as your SQL statement grow (in lengthand complexity), you’ll want to include descriptive comments(for your own future reference or for whoever has to work on theproject next). These comments need to be embedded in the SQLscripts, but they are obviously not intended for actual DBMSprocessing. (For an example of this, see the create.sql andpopulate.sql files used in Appendix B).
. The same is true for headers at the top of SQL file, perhaps con-taining the programmer contact information and a descriptionand notes. (This use case is also seen in the Appendix B .sqlfiles.).
. Another important use for comments is to temporarily stop SQLcode from being executed. If you were working with a long SQLstatement, and wanted to test just part of it, you could commentout some of the code so that DBMS saw it as comments andignored it.
Most DBMSs supports several forms of comment syntax. We’ll Start withinline comments:
Input ▼
SELECT prod_name -- this is a commentFROM Products;
Analysis ▼
Comments may be embedded inline using -- (two hyphens). Anythingafter the -- is considered comment text, making this a good option fordescribing columns in a CREATE TABLE statement, for example.
Here is another form of inline comment (although less commonly sup-ported):
Input ▼
# This is a commentSELECT prod_nameFROM Products;
Analysis ▼
A # at the start of a line makes the entire line a comment. You can see thisformat comment used in the accompanying create.sql andpopulate.sql scripts.
24 LESSON 2: Retrieving Data
You can also create multi line comments, and comments that stop andstart anywhere within the script:
Input ▼/* SELECT prod_name, vend_idFROM Products; */SELECT prod_nameFROM Products;
Analysis ▼
/* starts a comments, and */ ends it. Anything between /* and */ iscomment text. This type of comment is often used to comment out code,as seen in this example. Here, two SELECT statements are defined, but thefirst won’t execute because it has been commented out.
SummaryIn this lesson, you learned how to use the SQL SELECT statement toretrieve a single table column, multiple table columns, and all tablecolumns. You also learned how to return distinct values and how to com-ment your code. And unfortunately, you were also introduced to the factthat more complex SQL tends to be less portable SQL. Next you’ll learnhow to sort the retrieved data.
25Summary
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Symbols andNumerics
[] (brackets) wildcard,58-59
, (commas) characters, 16|| (concatenation)
operator, 63@ character, 193^ character, 59@@ERROR variable, 204@@IDENTITY global
variable, 195_ (underscore) wildcard,
57-58% (percent sign)
wildcard, 54| (pipe) symbol, 247
AABS() function, 79Access, using, 235accessing cursor data,
208-210adding rows to tables, 250advanced data filtering, 43advanced joins, creating,
125-128, 132-134aggregate functions, 81
ALL argument, 89AVG(), 82combining, 90COUNT(), 84-85DISTINCT
arguments, 89joins, 132-133MAX(), 85MIN(), 86-87SUM(), 87-88
aliases, 66-67, 91alternate uses, 67names, 68tables, 125-128, 132
Ccalculated fields, 61-63, 66
mathematical calcula-tions, 68-70
subqueries, 108-109views, 184
Cartesian Product, 117-119cascading delete
feature, 217case-sensitivity
sort orders, 33SQL statements, 16
CFQUERY CFQUERY tagpair, 234
CHAR string datatype, 255check constraints, 218checking
for no value, 40range of values, 40
clauses, 28ALL, 95HAVING, 96ordering, SELECT
statements, 101positioning, 42WHERE
combining, 43, 46joins, 117operators, 37positioning, 37-39
clients, formatting, 62CLOSE statements, closing
cursors, 211closing cursors, 211code, commenting, 72, 195codes, portable, 72ColdFusion (Allaire),
233-234columns, 7. See also fields
aliases, 66-68assigning new
values, 156
ALL argument, aggregatefunctions, 89
ALL clause, 95Allaire ColdFusion,
233-234ALTER TABLE statement,
169-170CHECK constraints, 219CONSTRAINT syntax,
215-217syntax, 248
AND operator, 43-44ANSI SQL, 11applications
data filtering, 36ODBC client, 245portable code, 72working in SQL, 233
Access, 235Allaire ColdFusion,
233-234DB2, 235Microsoft ASP, 236
argumentsaggregate, 90DISTINCT, 89
AS keyword, 66,126-129, 134
ASC keyword, 33ASP (Microsoft), 236-237authentication, 224authorization, 224AVG() function, 82
DISTINCT argument, 89NULL values, 83
BBETWEEN operator, 40BINARY datatype, 258BIT datatype, 256brackets ([]) wildcard,
58-59
Index
breaking data correctly, 8derived, 68foreign keys, 216GROUP BY clause, 95Identity fields, 195INSERT SELECT state-
ments, 151inserting omitting
columns, 149list (using INSERT
statements), 148naming, fully
qualified, 117NULL value, 40, 166padded spaces, 64primary keys, 9-10, 167retrieving, 14
all, 18multiple, 16unknown, 18
separating names inqueries, 16
sorting data, 30by mulitple columns,
29-30by non-selected
columns, 29-31descending on multiple
columns, 33specifying by relative
position, 96updating multiple, 156values, deleting, 157
combined queries, 137creating, 138-139sorting results, 143UNION statement
rules, 140combining
aggregate functions, 90WHERE clauses, 43, 46
commas (,), 16commenting code, 23-24,
72, 195COMMIT statements,
201, 248commits, 199comparing datatypes, 258compatibility
datatype, 8operator, 37
266 columns
savepoints, 203search patterns, 53stored procedures, 188,
191-194, 249tables, 163-165, 249triggers, 223views, 179
reusable, 180rules and
restrictions, 177uses, 177
CROSS JOIN, 119CT statement results, 21currency datatypes, 256cursors, 205
accessing data, 208-210closing, 211deallocating
resources, 211limitations, 206opening, 208options, 206using, 207Web-based
applications, 206Customers table, 227
Ddata
breaking correctly, 8calculated fields, 61Cartesian Product, 119consistency with stored
procedures, 189copying, table to
table, 152deleting, 157, 160filtering, 35
advanced, 43application level, 36checking against single
values, 38checking for a range of
values, 40checking for non-
matches, 38-39indexes, 221views, 183wildcards, 53
formatting, 17
complex joins, views, 179concatenating fields, 62concatenation operators, 63conditions (joins), 134configuring ODBC data
sources, 245CONSTRAINT syntax,
ALTER TABLE state-ments, 217
constraints, 213-214cautions, 214check, 218foreign keys, 216speed, 223syntax, 215unique, 217
copyingdata, table to table, 152tables, 152-153, 164
COS() function, 79COUNT() function, 82-85,
90, 133COUNT* subquery, 108CREATE INDEX state-
ment, 221, 248-249CREATE TABLE state-
ment, 163CONSTRAINT
syntax, 215DEFAULT keyword, 168required information, 164syntax, 249
CREATE VIEW statement,179, 249
creatingcalculated fields,
61-63, 66mathmatical calcula-
tions, 68-70subqueries, 108-109
ColdFusion pages,234, 242
combined queries,138-139
cursors, 207groups, 94-95indexes, 221, 248joins, 116
advanced, 125-126,132, 134
self, 126-127
How can we make this index more useful? Email us at [email protected]
267DELETE statement
grouping, 93, 99filtering groups, 96GROUP BY clause, 99nesting, 95ORDER BY
clause, 100inserting, 145-146, 219joins, 115manipulation
functions, 71date and time, 73,
76, 78numeric, 79
multiple occurences, 114numeric functions, 73ODBC database integra-
tion, 245referential integrity, 213retrieved
inserting, 150reformatting with
views, 180-183retrieving, 13, 81, 84-85
all columns, 18multiple columns, 16
security, 224sorting, 27, 99
by column position, 30by mulitple columns,
29-30by non-selected
columns, 29-31descending on multiple
columns, 33specifying direction, 31
summarizing, 81, 84-85text functions, 73transaction
processing, 198unsorted, 15updating, 155-156, 160
data and time datatypes, 257
Database ManagementSystem. See DBMS
databases, 5-6constraints, 214
check, 218syntax, 215unique, 217
datatypes, 254DB2, 235functions, 71indexes, 221interactive tools, 115joins, 121LIKE operator, 54security mechanisms, 224separating statements, 15specific operators, 41SQL extensions, 11stored procedures, 190transaction
processing, 200triggers, 223TRIM functions, 66UNION keyword, 139UNION statements, 143UPDATE statements, 155user-defined
datatypes, 219views
creating, 176rules and
restrictions, 178DECIMAL datatype, 256DECLARE statements
creating, cursors, 207stored procedures, 193
DEFAULT keyword, 168defining
datatypes, 216, 219foreign keys, 216ODBC Data Sources, 246primary keys, 10, 215
DELETE FROM statement, 158
DELETE statement, 157FROM keyword, 159guidelines, 160rollbacks, 201security privileges, 158syntax, 250transaction
processing, 199triggers, 222TRUNCATE TABLE
statement, 160WHERE clause, 158
cursorsaccessing data,
208-210closing, 211creating, 207opening, 208using, 207
dropping objects, 250filtering, 36indexes
cautions, 221creating, 221searching, 220
ODBC, 245order entry systems, 226scalability, 115schemas, 7search patterns, 53security, 224software, 6subqueries, 103tables, 6
creating, 163, 249triggers, 222
transaction processing, 197
datatypes, 8, 254binary, 258compatibility, 8currency, 256data and time, 257defining, 216, 219numeric, 256reasons for use, 253string, 254
date and time functions,73, 76-78
DATE dataype, 257DATEPART() function, 77DATETIME datatype, 257DB2, 235DBMS (Database
Management System), 6accidental table
deletion, 172affecting sort order, 28cascading delete
feature, 217constraints, 214cursor options, 206
deletingcascading delete
feature, 217column values, 157data, 157, 160rows, 250tables, 171
preventing accidentaldeletion, 172
derived columns. Seealiases
DESC keyword, 31dictionary sort order, 33displaying statement
output, 14DISTINCT argument
AVG() function, 89COUNT() function, 90
downloading ready-to-usedata files, 230
DROP statement,syntax, 250
DROP TABLE statement, 171
dropping database objects, 250
duplicate rows,eliminating, 141-142
Eeliminating duplicate rows,
141-142EQUIJOIN, 120establishing primary
keys, 10EXCEPT statements, 143EXECUTE statements,
190-191executing stored proce-
dures, 190-191EXP() function, 79explicit commits, 201extensions, 11
FFETCH statement,
208, 210fields, 62
aliases, 66alternate uses, 67names, 68
268 deleting
date and time, 73, 76-78numeric, 73, 79problems, 71system, 73text, 73text manipulation, 74
SOUNDEX() function, 75
UPPER() function, 73
Gglobal variables,
@@IDENTITY, 195GRANT statements, 224graphical interfaces, 115GROUP BY clause. See
also ORDER BY clausecreating groups, 94-95relative position of
columns, 96grouping
data, 93, 99GROUP BY clause, 99ORDER BY clause, 100
operators, 46groups
creating, 94-95filtering, 96nested, 95
H-IHAVING clauses, 96
Identity fields, 195implementing
transactions, 200IN operator, 47
advantages, 49combining with NOT
operator, 51including duplicate rows,
141-142indexes, 220
cautions, 221creating, 221, 248revisiting, 222searching, 220
inner joins, 120, 129INSERT SELECT
statement, 151
calculated, 61-63, 66mathematical
calculations, 68-70subqueries, 108-109views, 184
concatenating, 62filtering
by subquery, 104-105data, 35
advanced, 43application level, 36checking against single
values, 38checking for a range of
values, 40checking for non-
matches, 38-39indexes, 221views, 183
groups, 96wildcards, 53
fixed length strings, 254FLOAT datatype, 256foreign keys, 159, 216
benefits, 217defining, 216
formattingclients, 62data, 17retrieved data with views,
180-183servers, 62statements, 165subqueries, 106
FROM clause, 116FROM keyword
DELETE statement, 159UPDATE statement, 157
full outer joins, 132fully qualified column
names, 117functions, 71-72, 75
aggregate, 81AVG(), 82combining, 90COUNT(), 84-85DISTINCT, 89MAX(), 85MIN(), 86-87SUM(), 87-88
data manipulation, 71
How can we make this index more useful? Email us at [email protected]
269NOT operator
SELECT INTO state-ment comparison, 152
syntax, 251INSERT statement
columns lists, 148INTO keyword, 146omitting columns, 149partial rows, 149rollbacks, 204safety, 146security privileges, 145syntax, 250table layout, 147transaction
processing, 199triggers, 222VALUES, 148
insertingcolumns, 149data, 145-146
INTO keyword, 146retrieved, 150
rows, 146multiple, 152partial, 149-150
INT datatype, 256interactive DBMS
tools, 115INTERSECT
statements, 143INTO keyword, 146IS NULL clause, 41
Jjoining tables, 113, 115
aliases, 125-128, 132multiple, 121-123natural joins, 129performance
concerns, 121joins
aggregate functions,132-133
Cartesian Product, 117conditions, 134creating, 116
advanced, 125-128,132-134
self, 126-128
M managing transactions, 199
COMMIT statements, 201
ROLLBACK statements, 201
SAVEPOINT statements, 202
manipulating tables, 163complex structure
changes, 170deleting, 171
manipulation functions, 71date and time, 73, 76-78numeric, 79text, 74
mathematical calculations,performing, 68-70
mathematical operators, 69MAX() function, 82,
85-86, 90Microsoft Access. See
AccessMicrosoft ASP, 236-237Microsoft Query, 238MIN() function, 82, 86
DISTINCT argument, 90non-numeric data, 87
multiple tables,joining, 123
multiple rows,inserting, 152
MySQL, 240-241
Nnames, aliases, 126naming
aliases, 68, 91columns, fully
qualified, 117indexes, 221tables, renaming, 172
natural joins, 129navigating tables, 205NCHAR string
datatype, 255nested groups, 95NOT NULL values, 166NOT operator, 49-51, 60
CROSS, 119DBMS interactive
tools, 115EQUIJOIN, 120Inner, 120natural, 129outer, 129, 132
full, 132types, 132
performance considerations, 121
pros, 115self, instead of sub-
queries, 128types, 126views, 179WHERE clause, 117-119
Kkeys
foreign, 216primary, 9
keywords, 13AND, 44AS, 66, 126-129, 134DEFAULT, 168FROM, 157IN, 49INTO, 146NOT, 50OR, 45REFERENCES, 217UNION, 138UNIQUE, 218
Llanguages, SQL, 10,
259-263LEFT keyword, 131LIKE operator, 53-54limiting SELECT state-
ment results, 20-23local variables, @
character, 193LONG RAW datatype, 258LTRIM() function, 66
NULL values, 40AVG() functions, 83empty strings, 167primary keys, 167specifying, 167tables, 166
numeric datatypes, 256numeric functions, 73numeric manipulation
functions, 79NVARCHAR string
datatype, 255
Oobtaining sample tables
and scripts, 229ODBC
ASP, 236data sources, 245-246dates, 257versions, 245
omitting columns, 149OPEN CURSOR state-
ments, 208OPEN statements, opening
cursors, 208, 211opening cursors, 208, 211operators, 38
AND, 43-44BETWEEN, 40compatibility, 37concatenation, 63DBMS specific, 41grouping related, 46HAVING clause, 96IN, 47-49LIKE, 53mathematical, 69NOT, 49-51OR, 45predicates, 54WHERE clause, 37
OR operator, 45Oracle
commits, 202copying data between
tables, 153cursors
closing, 211creating, 208retrieving data, 208
270 NULL values
predicates, 54primary keys, 9-10
Customer table, 227defining, 10, 215NULL values, 167OrderItems table, 229Orders table, 228Products table, 227unique constraints, 217Vendors table, 226
processingstored procedures, 189subqueries, 106transactions, 198transactions. See
transaction processingProducts table, 226-227
QQMF (Qery Management
Facility) utility, 235queries, 103
aggregate functions, 81combined, 137
creating, 138-139sorting results, 143UNION statement
rules, 140WHERE clauses, 137
combining, 105data formatting, 17filtering results, 35internal query
optimizer, 140multiple WHERE
clauses, 140result sets, 205subqueries, 103table aliases, 126unsorted data results, 15views, 176wild cards (*), 18
quotesnumeric values, 256string values, 255
quotes (‘’), 39
RRAW datatype, 258ready-to-use data files,
downloading, 230
date and time manipula-tion functions, 77
savepoints, 203stored procedures,
191-194triggers, 223
Oracle 8, 241Oracle Express, 241ORDER BY clause, 99
positioning, 29SELECT statement, 28UNION statements, 142
order entry systems, 226order of evaluation
parenthesis, 47WHERE clauses, 46
ordering clauses, SELECTstatements, 101
OrderItems table, 228-229Orders table, 228outer joins, 129
full, 132syntax, 130types, 132
overwriting tables, 165
Ppadded spaces, 64parenthesis, 46-47partial rows, inserting,
149-150percent sign (%)
wildcard, 54performance
indexes, 221joins, 121SQL experimentation, 123subqueries, 108UNION statements, 140views, 177
PHP, 242PI() function, 79pipe (|) symbol, 247placeholders. See savepointsportable code, 72positioning
sorting data by columnposition, 30
WHERE clause, 37-39PostgreSQL, 243
How can we make this index more useful? Email us at [email protected]
271sorting
REAL datatype, 256REFERENCES
keyword, 217referential integrity,
213, 217reformatting retrieved data
with views, 180-183relational databases
referential integrity, 213sort order, 28
relational tables, 113-114relative position,
columns, 96RENAME statement, 172renaming tables, 172replacing tables, 165reserved words, 259-263restrictions, views, 177result sets, 205retrieving
columns, unknown, 18data, 13, 81, 84-85
all columns, 18FETCH statements,
208-210individual columns, 14inserting, 150mulitiple columns, 16
reusable views,creating, 180
revisiting indexes, 222REVOKE statements, 224RIGHT keyword, 131ROLLBACK statement,
201, 251rollbacks, 201
savepoints, 203statements, 204using, 199
rows, 9adding to tables, 250cursors, 205default values, 168deleting, 250duplicate, 141-142filtering, 96inserting, 146
check constraints, 219multiple, 152partial, 149-150
DISTINCT keyword,19-20
FROM clause, 116GROUP BY clause, 94inner joins, 130, 133IS NULL clause, 41joins, 115-116ORDER BY clause, 28
DESC keyword, 31positioning, 29
results, limiting, 20-23retrieving individual
columns, 14subqueries, 104-106, 110syntax, 252UNION keyword,
138-140WHERE clause, 35
combined queries, 137combining, 44IN operator, 47NOT operator, 49-51OR operators, 45quotes, 39
self-joins, creating,126-128
semicolons (;), 15separating statements, 15sequence (clauses), 101servers, formatting, 62SET command, 156simplifying joins with
views, 179SIN() function, 79Single Column Only
subqueries, 107SMALLDATETIME
datatype, 257SMALLINT datatype, 256sorting
by non-selected columns, 29
case-sensitivity issues, 33combined query
results, 143data, 27, 99
by column position, 30descending on multiple
columns, 33
joins, 129returning with UNION
statements, 141updating, 252
RTRIM() function, 64-65rules
constraints, 214views, 177
Ssamples
scripts, obtaining, 229tables, 226, 229
SAVEPOINT statements, 202
savepoints, 199, 203-204scalablity, 115scale, 115schemas, 7scripts
ASP.NET, 237comments, 23-24downloading, 230PHP, 242samples, obtaining, 229
search patterns, 53-55searching
indexes, 220wildcards, 53
% character, 54[] characters, 58-59^ character, 59_ character, 57-58
securitydata, 224DELETE statement, 158INSERT statements, 145UPDATE statement, 155
SELECT * FROM statements, 179
SELECT INTO statements, 152
SELECT statement, 13AS keyword, 66AVG() function, 82clauses, ordering, 101concatenating columns,
63-64creating groups, 94-95
multiple columns,29-30
non-selected columns, 31
ORDER BY clause, 100
retrieved, 27specifying direction, 31
datatype functionality,253, 262
SOUNDEX() function, 75spaces, padded, 64specifying
dates, 257defualt values, 168NULL values, 167sort direction, 31statements, 14
speedconstraints versus
triggers, 223deleting data, 160
SQL, 10advanced features, 213advantages, 11ALL clause, 95column aliases, 66commits, 201cursors
closing, 211creating, 207retrieving data, 210
DATEPART() function, 77
deleting/updating data, 161
experimentation withoperations, 123
extensions, 11Identity fields, 195INNER JOIN
syntax, 120INSERT statements, 146keywords, 13local variables, @
character, 193reserved words, 259-263savepoints, 203statements, clauses, 28stored procedures, 193
272 sorting
results, limiting, 20-23syntax, 252
specifying, 14stored procedures. See
stored proceduressyntax, 247terminating, 15UNION, 138-140UPDATE, 155-156,
160, 252white space, 16writing, 225
stored procedures, 187benefits, 189commenting code, 195creating, 188,
191-194, 249executing, 190-191functionality, 194Identity fields, 195justification, 188Oracle, 191-194syntax, 189triggers, 222
storingdatatype
functionality, 253date and time values, 257numeric values, 255strings, 254
string datatypes, 254strings
fixed length, 254quotes, 255search, wildcards, 54variable-length, 254
subqueries, 103calculated fields, 108-109COUNT*, 108filtering by, 104-105formatting, 106joins, 127performance, 108processing, 106SELECT statement, 104self joins instead, 128Single Column Only, 107UPDATE statement, 157WHERE lauses, 107
SUM() function, 82, 87-88
transaction processing, 200
triggers, 223working in popular appli-
cations, 233SQL Server Management
Studio, 239SQRT() function, 79statements
ALTER TABLE,169-170, 248
case, 16CFQUERY/CFQUERY
tag pairs, 234clauses, 28COMMIT, 248CREATE INDEX, 221,
248-249CREATE TABLE
required information, 164
syntax, 249CREATE VIEW,
179, 249DELETE, 157, 160
FROM keyword, 159syntax, 250
displaying output, 14DROP, 250DROP TABLE, 171formatting, 165GRANT, 224grouping related
operators, 46INSERT
omitting columns, 149safety, 146security privileges, 145syntax, 250VALUES, 148
INSERT SELECT,syntax, 251
OPEN CURSOR, 208RENAME, 172REVOKE, 224ROLLBACK,
syntax, 251rollbacks, 199, 204SELECT, 13
DISTINCT keyword,19-20
How can we make this index more useful? Email us at [email protected]
273trimming padded spaces
summarizing data,81, 84-85
syntaxALTER TABLE
statement, 248COMMIT statement, 248constraints, 215CREATE INDEX
statement, 248-249CREATE TABLE
statement, 249CREATE TABLE
statements, 163CREATE VIEW
statement, 249DELETE statement, 250DROP statement, 250INERT statement, 251INSERT statement, 250outer joins, 130ROLLBACK
statement, 251SELECT statement, 252statements, 247stored procedures, 189transaction
processing, 200triggers, 223UPDATE statement, 252
system functions, 73
Ttables, 6
aliases, 125-128, 132calculated fields, 61columns, 7
NULL value, 40primary keys, 10
constraints, 214check, 218syntax, 215unique, 217
copying, 152-153, 164copying data to
tables, 152creating, 163-165, 249cursors
accessing data,208-210
viewscreating, 249uses, 176
virtual, 175-176tags, ColdFusion, 234TAN() function, 79terminating statements, 15text manipulation func-
tions, 74SOUNDEX()
function, 75UPPER() function, 73
TEXT string datatype, 255TINYINT datatype, 256tools, DBMS
interactive, 115TOP argument, 90TOP PERCENT
argument, 90to_char() function, 78to_number() functions, 78transactions, 197
blocks, ROLLBACKstatements, 251
COMMIT statements, 201
implementing, 200managing, 199
COMMIT statements, 201
ROLLBACK statements, 201
SAVEPOINT statements, 202
ROLLBACK statements, 201
SAVEPOINT statements, 202
savepoints, 199, 204writing to databases, 248
triggerscreating, 223functionality, 222speed, 223syntax examples, 223
TRIM() function, 66trimming padded
spaces, 64
closing, 211creating, 207opening, 208
Customer, 227data, copying, 153datatypes, 8deleting, 171-172deleting data, 157-159indexes
cautions, 221creating, 221searching, 220
inserting data, 146multiple rows, 152partial rowas, 149retrieved, 150
joining, 113-115aliases, 132Cartesian Product, 117multiple, 121-123natural joins, 129performance
concerns, 121manipulating, 163NULL values, 166OrderItems, 228-229Orders, 228Products, 226-227referential integrity, 213relational, 113-114renaming, 172replacing existing, 165rows, 9
adding, 250cursors, 205deleting, 250filtering, 96updating, 252
samples, 226, 229schemas, 7security, 224stored procedures, 189triggers, 222
creating, 223functionality, 222
updating, 155-156,169-170
Vendors, 226
troubleshooting accidentaltable deletion, 172
TRUNCATE TABLE statement, 160
Uunderscore (_)
wildcard, 57-58UNION ALL
statements, 142UNION statements
combined queries,creating, 138-139
duplicate row handling, 141
limits, 140ORDER BY clause, 142rules, 140types, 143UNION, 140
unions. See combinedqueries
unique constraints, 217UNIQUE keyword, 218unsorted data, 15UPDATE statement
cautions, 155FROM keyword, 157guidelines, 160security privileges, 155SET command, 156subqueries, 157syntax, 252table names, 156transaction
processing, 199triggers, 222WHERE clause, 156
updatingdata, 155-156, 160multiple columns, 156tables, 169-170
UPPER() function, 73user-defined datatypes, 219
274 troubleshooting accidental table deletion
operators, 37OR operators, 45parenthesis, 47positioning, 37, 39quotes, 39SOUNDEX()
function, 76subqueries, 107UPDATE statements,
155-156wildcards, 53
white space, SQL statements, 16
whitespace, 16wildcards, 18, 53
[] (brackets) characters,58-59
_ (underscore) character,57-58
^ character, 59natural joins, 129positioning in search
patterns, 55search patterns, 55
wrappers, ODBC, 245writing
SQL statements, 225stored procedures, 189
Vvalues
columns, deleting, 157concatenation, 63default, 168NULL, 167searching for
(indexes), 220trimming padded
space, 65VARBINARY
datatype, 258variable-length strings, 254Vendors table, 226views
calculated fields, 184creating, 177-180, 249DBMS consistency, 176filtering unwanted
data, 183joins, 179performance
concerns, 177reformatting retrieved
data, 180-183rules and
restrictions, 177SELECT statement, 175uses, 176
virtual tables, 175-176
W-X-Y-Zweb-based applications,
cursors, 206WHERE clause, 35
BETWEEN operator, 40combining, 43
order of evaluation, 46with queries, 137
DELETE statements, 158filtering, 97IN operator, 47joins, 117-119NOT operators, 49, 51