ptg ptg Praise for Database Design for Mere Mortals ™ , Second Edition “This book takes the somewhat daunting process of database design and breaks it into completely manageable and understandable components. Mike’s ap- proach whilst simple is completely professional, and I can recommend this book to any novice database designer.” —Sandra Barker, Lecturer, University of South Australia, Australia “Databases are a critical infrastructure technology for information systems and today’s business. Mike Hernandez has written a literate explanation of data- base technology—a topic that is intricate and often obscure. If you design data- bases yourself, this book will educate you about pitfalls and show you what to do. If you purchase products that use a database, the book explains the tech- nology so that you can understand what the vendor is doing and assess their products better.” —Michael Blaha, consultant and trainer, author of A Manager’s Guide to Database Technology “If you told me that Mike Hernandez could improve on the first edition of Data- base Design for Mere Mortals I wouldn’t have believed you, but he did! The sec- ond edition is packed with more real-world examples, detailed explanations, and even includes database-design tools on the CD-ROM! This is a must-read for anyone who is even remotely interested in relational database design, from the individual who is called upon occasionally to create a useful tool at work, to the seasoned professional who wants to brush up on the fundamentals. Simply put, if you want to do it right, read this book!” —Matt Greer, Process Control Development, The Dow Chemical Company “Mike’s approach to database design is totally common-sense based, yet he’s ad- hered to all the rules of good relational database design. I use Mike’s books in my starter database-design class, and I recommend his books to anyone who’s interested in learning how to design databases or how to write SQL queries.” —Michelle Poolet, President, MVDS, Inc. ptg “Slapping together sophisticated applications with poorly designed data will hurt you just as much now as when Mike wrote his first edition, perhaps even more. Whether you’re just getting started developing with data or are a seasoned pro; whether you’ve read Mike’s previous book or this is your first; whether you’re happier letting someone else design your data or you love doing it your- self—this is the book for you. Mike’s ability to explain these concepts in a way that’s not only clear, but fun, continues to amaze me.” —From the Foreword by Ken Getz, MCW Technologies, coauthor ASP.NET Developer’s JumpStart “The first edition of Mike Hernandez’s book Database Design for Mere Mortals was one of the few books that survived the cut when I moved my office to smaller quarters. The second edition expands and improves on the original in so many ways. It is not only a good, clear read, but contains a remarkable quantity of clear, concise thinking on a very complex subject. It’s a must for anyone inter- ested in the subject of database design.” —Malcolm C. Rubel, Performance Dynamics Associates “Mike’s excellent guide to relational database design deserves a second edition. His book is an essential tool for fledgling Microsoft Access and other desktop da- tabase developers, as well as for client/server pros. I recommend it highly to all my readers.” —Roger Jennings, author of Special Edition Using Access 2002 “There are no silver bullets! Database technology has advanced dramatically, the newest crop of database servers perform operations faster than anyone could have imagined six years ago, but none of these technological advances will help fix a bad database design, or capture data that you forgot to include! Data- base Design for Mere Mortals™, Second Edition, helps you design your database right in the first place!” —Matt Nunn, Product Manager, SQL Server, Microsoft Corporation ptg “When my brother started his professional career as a developer, I gave him Mike’s book to help him understand database concepts and make real-world ap- plication of database technology. When I need a refresher on the finer points of database design, this is the book I pick up. I do not think that there is a better testimony to the value of a book than that it gets used. For this reason I have wholeheartedly recommended to my peers and students that they utilize this book in their day-to-day development tasks.” —Chris Kunicki, Senior Consultant, OfficeZealot.com “Mike has always had an incredible knack for taking the most complex topics, breaking them down, and explaining them so that anyone can ‘get it.’ He has honed and polished his first very, very good edition and made it even better. If you’re just starting out building database applications, this book is a must-read cover to cover. Expert designers will find Mike’s approach fresh and enlightening and a source of great material for training others.” —John Viescas, President, Viescas Consulting, Inc., author of Running Microsoft Access 2000 and coauthor of SQL Queries for Mere Mortals “Whether you need to learn about relational database design in general, design a relational database, understand relational database terminology, or learn best practices for implementing a relational database, Database Design for Mere Mor- tals™, Second Edition, is an indispensable book that you’ll refer to often. With his many years of real-world experience designing relational databases, Michael shows you how to analyze and improve existing databases, implement keys, de- fine table relationships and business rules, and create data views, resulting in data integrity, uniform access to data, and reduced data-entry errors.” —Paul Cornell, Site Editor, MSDN Office Developer Center ptg Praise for the First Edition “[A]n astoundingly fresh approach to the ‘nasty’ task of database design . . . Anyone who has anything to do with creating applications using a database product should buy this book and read it cover to cover.” —John Viescas, President, Viescas Consulting, Inc., author of Running Microsoft Access 2000 and coauthor of SQL Queries for Mere Mortals “[A] must-have for anyone new to relational database design . . . [Mike’s] atten- tion to detail is marvelous, and the explanations of the interview process are a must-read for anyone, including experienced relational database designers.” —Jim Booth, Principal Consultant, James Booth Consulting “Mike has done us a favor by taking an academic topic and making it logical, ap- proachable, and comprehensible for us mortals. Anyone interested in making their database design better should read this book. It contains good information for every level of database developer.” —Malcolm C. Rubel, Contributing Editor, Databased Advisor and FoxPro Advisor “Database Design for Mere Mortals is sure to help both aspiring and practicing database designers alike! Michael delivers the major points of logical database design with a clear, common-sense approach that makes this book an excellent resource and a pleasure to read.” —Nick Evans, Contributing Editor, PowerBuilder Advisor Magazine “No matter what specific database package you’re using (or, perhaps, no pack- age at all), the concepts in this book will make sense, and will apply to your da- tabase design projects.” —From the Foreword by Ken Getz, MCW Technologies, coauthor, ASP.NET Developer’s JumpStart ptg Database Design for Mere Mortals ™ Second Edition ptg Addison-Wesley presents the For Mere Mortals ® Series Series Editor: Michael J. Hernandez The goal of the For Mere Mortals ® Series is to present you with information on important technology topics in an easily accessible, common-sense manner.The primary audience for Mere Mortals books is that of readers who have little or no background or formal training in the subject matter. Books in the Series avoid dwelling on the theoretical and instead take you right into the heart of the topic with a matter-of-fact,hands-on approach. The books are not designed to address all the intricacies of a given technology, but they do not avoid or gloss over complex, essential issues either. Instead, they focus on provid- ing core, foundational knowledge in a way that is easy to understand and that will prop- erly ground you in the topic.This practical approach provides you with a smooth learning curve and helps you to begin to solve your real-world problems immediately. It also pre- pares you for more advanced treatments of the subject matter, should you decide to pur- sue them, and even enables the books to serve as solid reference material for those of you with more experience.The software-independent approach taken in most books within the Series also teaches the concepts in such a way that they can be applied to whatever particular application or system you may need to use. Titles in the Series: Project Management for Mere Mortals ® Claudia M. Baca. ISBN: 0321423453 User Interface Design for Mere Mortals™ Eric Butow. ISBN: 0321447735 Database Design for Mere Mortals ® , Second Edition: A Hands-On Guide to Relational Database Design Michael J. Hernandez. ISBN: 0201752840 Microsoft Office Project for Mere Mortals®: Solving the Mysteries of Microsoft Office Project Patti Jansen. ISBN: 0321423429 UML for Mere Mortals ® Robert A. Maksimchuk and Eric J. Naiburg. ISBN: 0321246241 VSTO for Mere Mortals™ Kathleen McGrath and Paul Stubbs. ISBN: 0321426711 SQL Queries for Mere Mortals®: A Hands-On Guide to Data Manipulation in SQL, Second Edition John L.Viescas and Michael J. Hernandez. ISBN: 0321444434 For more information, check out the series web site at www.awprofessional.com/ForMereMortalsSeries. ptg Database Design for Mere Mortals ™ Second Edition A Hands-On Guide to Relational Database Design Michael J. Hernandez Boston • San Francisco • New York • Toronto • Montreal London • Munich • Paris • Madrid Capetown • Sydney • Tokyo • Singapore • Mexico City   ptg 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 Addison-Wesley was aware of a trademark claim, the designations have been printed with initial capital letters or in all capitals. The author 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 con- nection with or arising out of the use of the information or programs contained herein. The publisher offers discounts on this book when ordered in quantity for bulk pur- chases and special sales. For more information, please contact: U.S. Corporate and Government Sales (800) 382-3419 corpsales@pearsontechgroup.com For sales outside of the U.S., please contact: International Sales (317) 581-3793 international@pearsontechgroup.com Visit Addison-Wesley on the Web: www.awprofessional.com Library of Congress Cataloging-in-Publication Data Hernandez, Michael J. (Michael James), 1955– Database design for mere mortals : a hands-on guide to relational database design / Michael J. Hernandez—2nd ed. p. cm. Includes bibliographic references and index. ISBN 0-201-75284-0 (alk. paper) 1. Database design. 2. Relational databases. I. Title. QA76.9.D26 H477 2003 005.75'6—dc21 2002034545 Copyright © 2003 by Michael J. Hernandez. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form, or by any means, electronic, mechani- cal, photocopying, recording, or otherwise, without the prior consent of the pub- lisher. Printed in the United States of America. Published simultaneously in Canada. For information on obtaining permission for use of material from this work, please submit a written request to: Pearson Education, Inc. Rights and Contracts Department 75 Arlington Street, Suite 300 Boston, MA 02116 Fax: (617) 848-7047 ISBN 0-201-75284-0 Text printed in the United States on recycled paper at Courier Stoughton in Stoughton, Massachusetts. 6 7 8 9 10—CRS—07060504 Printing 13th February 2008 ptg For my wife, Kendra, who has always believed in me. In loving memory of our cats, Chico and Bugs. Writing just isn’t the same without them. Dedicated to anyone who has unsuccessfully attempted to design a relational database. [...]... intricacies and nuances of design and so will you —MICHAEL J HERNANDEZ DATABASE DESIGN FOR MERE MORTALS In the six years since the first edition of this book was published, I’ve continued my journey along the database path I’ve dug deeper into the intracacies of design and probed further into the philosophy of good design I’ve learned much from numerous conversations with my database students and industry... had embarked She determined that this would be a good time for me to work on realizing my goal—to finally commit to paper all that I had learned about database design The book you now hold in your hands is a result of the culmination of this particular journey I’ve shaped and molded the knowledge I accumulated into what I believe is a clear and straightforward databasedesign method I’ve tried very hard... This Book Is Organized xlvi Part I: Relational Database Design xlvi Part II: The Design Process xlvi Part III: Other Database- Design Issues xlviii Part IV: Appendixes xlviii A Word About the Examples and Techniques in This Book A New Approach to Learning l PART I: RELATIONAL DATABASE DESIGN Chapter 1: The Relational Database Topics Covered in This Chapter 3 Types of Databases 4 Early Database Models 5... with Database Design? The Importance of Theory 29 The Advantage of Learning a Good Design Methodology Objectives of Good Design 32 Benefits of Good Design 33 Database- Design Methods 34 Traditional Design Methods 34 The Design Method Presented in This Book 36 Summary 40 Review Questions 41 Chapter 3: Terminology 43 Topics Covered in This Chapter 43 Why This Terminology Is Important 44 Value-Related Terms... Level of Views 485 Assembling the Database Documentation Done at Last! 487 Case Study—Wrap Up 487 Summary 488 xxi 481 482 483 486 PART III: OTHER DATABASE- DESIGN ISSUES Chapter 14: Bad Design What Not to Do 491 Topics Covered in This Chapter 491 Flat-File Design 492 Spreadsheet Design 493 Dealing with the Spreadsheet View Mind-set 495 Database Design Based on the Database Software 497 A Final Thought... understand So I wrote a special report on the fundamentals of database design for a local publisher, and it met with some success Encouraged by this, I decided that someday I would write a book on the complete process of relational database design Early in my journey, I became a successful database developer and instructor I’ve developed databases for a number of diverse organizations and businesses... for data, and well-designed data Slapping together sophisticated applications with poorly designed data will hurt you just as much now as when Mike wrote his first edition— perhaps even more Whether you’re just getting started developing with data, or are a seasoned pro; whether you’ve read Mike’s previous book, or this is your first time; whether you’re happier letting someone else design your data,... little available The few attempts at “simpli ed texts simply failed to teach effectively, often because the authors seemed to assume that the reader was simpleminded I believed that there should be a book for people who did not have high levels of specialized education; a book that was straightforward and easy to read, thorough but not tedious; a book that used examples that were relatively easy to understand... Database Model The Network Database Model 9 xlix 1 3 5 xiii xiv Contents The Relational Database Model 12 Retrieving Data 15 Advantages of a Relational Database 17 Relational Database Management Systems 18 Beyond the Relational Model What the Future Holds 22 A Final Note 24 Summary 24 Review Questions 26 21 Chapter 2: Design Objectives 27 Topics Covered in This Chapter 27 Why Should You Be Concerned... this: Well, Ked, now we can take a nice, long, well-deserved break This page intentionally left blank Preface (First Edition) If the Lord Almighty had consulted me before embarking upon Creation, I should have recommended something simpler —ALFONSO X, KING OF CASTILE AND LEON Creating a database can be like creating a universe, only more complicated At least when the universe was created, there was . JumpStart ptg Database Design for Mere Mortals ™ Second Edition ptg Addison-Wesley presents the For Mere Mortals ® Series Series Editor: Michael J. Hernandez The goal of the For Mere Mortals ® Series. developer.” —Malcolm C. Rubel, Contributing Editor, Databased Advisor and FoxPro Advisor Database Design for Mere Mortals is sure to help both aspiring and practicing database designers alike! Michael delivers. web site at www.awprofessional.com/ForMereMortalsSeries. ptg Database Design for Mere Mortals ™ Second Edition A Hands-On Guide to Relational Database Design Michael J. Hernandez Boston • San