SQL VISUAL QUICKSTART GUIDE- P1 pps

Visual QuickStart GuideSQL, Third Edition Chris Fehily Peachpit Press 1249 Eighth Street Berkeley, CA 94710 510/524-2178 510/524-2221 fax Find us on the Web at www.peachpit.com To report

Peachpit Press

VISUAL QUICKSTART GUIDE

SQL

Third Edition

Chris Fehily

Visual QuickStart Guide

SQL, Third Edition

Chris Fehily

Peachpit Press

1249 Eighth Street

Berkeley, CA 94710

510/524-2178

510/524-2221 (fax)

Find us on the Web at www.peachpit.com

To report errors, please send a note to errata@peachpit.com

Peachpit Press is a division of Pearson Education

Copyright © 2008 by Chris Fehily

Editor: Cliff Colby

Copy Editor: Kim Wimpsett

Production Coordinator: Tracey Croom

Compositor: David Van Ness

Indexer: Rebecca Plunkett

Cover Design: Peachpit Press

Notice of Rights

All rights reserved No part of this book may be reproduced or transmitted in any form by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher For information on getting permission for reprints and excerpts, contact permissions@peachpit.com

Notice of Liability

The information in this book is distributed on an “As Is” basis, without warranty While every precaution has been taken in the preparation of the book, neither the author nor Peachpit Press shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the instructions contained in this book or by the computer software and hardware products described in it

Trademarks

Visual QuickStart Guide is a registered trademark of Peachpit Press, a division of Pearson Education

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 Peachpit was aware of a trademark claim, the designations appear as requested by the owner of the trademark All other product names and services identified throughout this book are used in editorial fashion only and for the benefit of such companies with no intention of infringement of the trademark No such use,

or the use of any trade name, is intended to convey endorsement or other affiliation with this book ISBN 13: 978-0-321-55357-7

ISBN 10: 0-321-55357-8

9 8 7 6 5 4 3 2 1

Printed and bound in the United States of America

For my father, Jack Fehily

Special thanks to…

Cliff Colby for two in a row Kim Wimpsett for the hyphenectomy Tracey Croom and David Van Ness for kerning above and beyond

Rebecca Plunkett for the subsubentries Troels Arvin (technical editor for the second edition), Bryan Steinweg (technical editor for the first edition), Russ Abbott, Darren Pennington for their suggestions and technical help

The data in the sample database are fictional I lifted two book titles from Iain M Banks’ Culture novels

v

About SQL xii

About This Book xvi

What You’ll Need xx

Chapter 1: DBMS Specifics 1 Running SQL Programs 2

Microsoft Access 5

Microsoft SQL Server 10

Oracle 17

IBM DB2 20

MySQL 27

PostgreSQL 30

Chapter 2: The Relational Model 33 Tables, Columns, and Rows 34

Primary Keys 38

Foreign Keys 40

Relationships 42

Normalization 45

The Sample Database 51

Creating the Sample Database 57

Chapter 3: SQL Basics 61 SQL Syntax 62

SQL Standards and Conformance 65

Identifiers 66

Data Types 68

Character String Types 70

Binary Large Object Type 72

Exact Numeric Types 73

Approximate Numeric Types 75

Boolean Type 76

Datetime Types 77

Interval Types 80

Unique Identifiers 82

Other Data Types 83

Nulls 84

Chapter 4: Retrieving Data from a Table 87

Retrieving Columns with SELECTandFROM 88

Creating Column Aliases with AS 91

Eliminating Duplicate Rows with DISTINCT 93

Sorting Rows with ORDER BY 95

Filtering Rows with WHERE 101

Combining and Negating Conditions with AND,OR, and NOT 105

Matching Patterns with LIKE 114

Range Filtering with BETWEEN 118

List Filtering with IN 121

Testing for Nulls with IS NULL 124

Chapter 5: Operators and Functions 127 Creating Derived Columns 128

Performing Arithmetic Operations 130

Determining the Order of Evaluation 133

Concatenating Strings with || 134

Extracting a Substring with SUBSTRING() 137

Changing String Case with UPPER() andLOWER() 140

Trimming Characters with TRIM() 142

Finding the Length of a String with CHARACTER_LENGTH() 147

Finding Substrings with POSITION() 149

Performing Datetime and Interval Arithmetic 152

Getting the Current Date and Time 154

Getting User Information 156

Converting Data Types with CAST() 157

Evaluating Conditional Values with CASE 161

Checking for Nulls with COALESCE() 165

Comparing Expressions with NULLIF() 166

Chapter 6: Summarizing and Grouping Data 169 Using Aggregate Functions 170

Creating Aggregate Expressions 171

Finding a Minimum with MIN() 172

Finding a Maximum with MAX() 173

Calculating a Sum with SUM() 174

Calculating an Average with AVG() 175

Counting Rows with COUNT() 178

Aggregating Distinct Values with DISTINCT 179

Grouping Rows with GROUP BY 183

Filtering Groups with HAVING 190

vii

Table of Contents

Table of Contents

Qualifying Column Names 194

Creating Table Aliases with AS 196

Using Joins 198

Creating Joins with JOINorWHERE 200

Creating a Cross Join with CROSS JOIN 204

Creating a Natural Join with NATURAL JOIN 206

Creating an Inner Join with INNER JOIN 210

Creating Outer Joins with OUTER JOIN 235

Creating a Self-Join 247

Chapter 8: Subqueries 253 Understanding Subqueries 254

Subquery Syntax 256

Subqueries vs Joins 257

Simple and Correlated Subqueries 262

Qualifying Column Names in Subqueries 267

Nulls in Subqueries 268

Using Subqueries as Column Expressions 270

Comparing a Subquery Value by Using a Comparison Operator 275

Testing Set Membership with IN 281

Comparing All Subquery Values with ALL 288

Comparing Some Subquery Values with ANY 291

Testing Existence with EXISTS 294

Comparing Equivalent Queries 301

Chapter 9: Set Operations 303 Combining Rows with UNION 304

Finding Common Rows with INTERSECT 310

Finding Different Rows with EXCEPT 312

Chapter 10: Inserting, Updating, and Deleting Rows 315 Displaying Table Definitions 316

Inserting Rows with INSERT 319

Updating Rows with UPDATE 327

Deleting Rows with DELETE 333

Chapter 11: Creating, Altering, and Dropping Tables 337 Creating Tables 338

Understanding Constraints 339

Creating a New Table with CREATE TABLE 341

Forbidding Nulls with NOT NULL 343

Specifying a Default Value with DEFAULT 346

Table of Contents

Specifying a Primary Key with

PRIMARY KEY 350

Specifying a Foreign Key with FOREIGN KEY 353

Forcing Unique Values with UNIQUE 359

Adding a Check Constraint with CHECK 363

Creating a Temporary Table with CREATE TEMPORARY TABLE 366

Creating a New Table from an Existing One with CREATE TABLE AS 369

Altering a Table with ALTER TABLE 373

Dropping a Table with DROP TABLE 376

Chapter 12: Indexes 377 Creating an Index with CREATE INDEX 378

Dropping an Index with DROP INDEX 383

Chapter 13: Views 385 Creating a View with CREATE VIEW 386

Retrieving Data Through a View 391

Updating Data Through a View 394

Dropping a View with DROP VIEW 398

Chapter 14: Transactions 399 Executing a Transaction 400

Chapter 15: SQL Tricks 405 Calculating Running Statistics 406

Generating Sequences 409

Finding Sequences, Runs, and Regions 415

Limiting the Number of Rows Returned 421

Assigning Ranks 430

Calculating a Trimmed Mean 432

Picking Random Rows 433

Handling Duplicates 435

Creating a Telephone List 438

Retrieving Metadata 439

Working with Dates 445

Calculating a Median 451

Finding Extreme Values 453

Changing Running Statistics Midstream 454

Pivoting Results 456

Working with Hierarchies 458