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eBooks from Alan Beaulieu
All books and eBooks by Alan Beaulieu:
Learning SQL
Learning SQL, Second Edition by Alan Beaulieu Copyright © 2009 O’Reilly Media, Inc. All rights reserved. Printed in the United States of America. Published by O’Reilly Media, Inc., 1005 Gravenstein Highway North, Sebastopol, CA 95472. O’Reilly books may be purchased for educational, business, or sales promotional use. Online editions are also available for most titles (http://safari.oreilly.com). For more information, contact our corporate/ institutional sales department: (800) 998-9938 or corporate@oreilly.com. Editor: Mary E. Treseler Indexer: Ellen Troutman Zaig Production Editor: Loranah Dimant Cover Designer: Karen Montgomery Copyeditor: Audrey Doyle Interior Designer: David Futato Proofreader: Nancy Reinhardt Illustrator: Robert Romano Printing History: August 2005: First Edition. April 2009: Second Edition. Nutshell Handbook, the Nutshell Handbook logo, and the O’Reilly logo are registered trademarks of O’Reilly Media, Inc. Learning SQL, the image of an Andean marsupial tree frog, and related trade dress are trademarks of O’Reilly Media, Inc. Many of the designations used
(2009)
Mastering Oracle SQL
by Sanjay Mishra and Alan Beaulieu
Chapter 1 CHAPTER 1 Introduction to SQL In this introductory chapter, we explore the origin and utility of the SQL language, demonstrate some of the more useful features of the language, and define a simple database design from which most examples in the book are derived. What Is SQL? SQL is a special-purpose language used to define, access, and manipulate data. SQL is nonprocedural, meaning that it describes the necessary components (i.e., tables) and desired results without dictating exactly how those results should be computed. Every SQL implementation sits atop a database engine, whose job it is to interpret SQL statements and determine how the various data structures in the database should be accessed to accurately and efficiently produce the desired outcome. The SQL language includes two distinct sets of commands: Data Definition Lan- guage (DDL) is the subset of SQL used to define and modify various data structures, while
(2007)
Learning SQL
Chapter 1 CHAPTER 1 A Little Background Before we roll up our sleeves and get to work, it might be beneficial to introduce some basic database concepts and look at the history of computerized data storage and retrieval. Introduction to Databases A database is nothing more than a set of related information. A telephone book, for example, is a database of the names, phone numbers, and addresses of all people liv- ing in a particular region. While a telephone book is certainly a ubiquitous and fre- quently used database, it suffers from the following: • Finding a person’s telephone number can be time consuming, especially if the telephone book contains a large number of entries. • A telephone book is only indexed by last/first names, so finding the names of the people living at a particular address, while possible in theory, is not a practical use for this database. •
(2005)
