tailieunhanh - Database Design by Ryan K. Stephens Ronald R. Plew

This chapter presents the relational model and three relational languages. The rela- tional model (Section ) is used extensively throughout the text as is the relational algebra (Section ). The chapter also covers the tuple relational calculus (Section ) and domain relational calculus (Section ) (which is the basis of the QBE language described in Chapter 5). Classes that emphasize only SQL may omit the relational calculus languages. Our notation for the tuple relational calculus makes it easy to present the con- cept of a safe query. The concept of safety for the domain relational calculus, though identical to that for the tuple calculus, is much more cumbersome. | Ryan K. Stephens and Ronald R. Plew Database Design Master the concepts understand database fundamentals Examine relational database architecture and design Plan a database design effort Analyze and model business requirements imp ement database security Apply database design concepts Learn relational database design from planning and logical design to physical design and implementation considerations Build databases via practical examples and real-world case studies that apply the concepts explained In the book Distinguish from relational to object-oriented flat-file and hierarchical databases via comparisons Follow the best practices of database design from Vie ground up with Innovative solutions to common pitfalls. Database Design Ryan K. Stephens Ronald R. Plew SẨMS 800 East 96th St. Indianapolis Indiana 46240 USA Database Design Copyright 2001 by Sams Publishing All rights reserved. No part of this book shall be reproduced stored in a retrieval system or transmitted by any means electronic mechanical photocopying recording or otherwise without written permission from the publisher. No patent liability is assumed with respect to the use of the information contained herein. Although every precaution has been taken in the preparation of this book the publisher and author assume no responsibility for errors or omissions. Nor is any liability assumed for damages resulting from the use of the information contained herein. International Standard Book Number 0-672-31758-3 Library of Congress Catalog Card Number 99-63863 Printed in the United States of America First Printing November 2000 03 02 01 00 4 3 2 1 Trademarks All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Sams cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark. Warning and Disclaimer Every effort has been made to make this book as

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