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FUNDAMENTALS OF DATABASE

MANAGEMENT SYSTEMS

Second Edition

MARK L. GILLENSON Fogelman College of Business and Economics

University of Memphis

John Wiley & Sons, Inc.

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Library of Congress Cataloging-in-Publication Data

Gillenson, Mark L. Fundamentals of database management systems / Mark L. Gillenson.—2nd ed.

p. cm. Includes index. ISBN 978-0-470-62470-8 (pbk.) 1. Database management. I. Title. QA76.9.D3G5225 2011 005.74—dc23

2011039274

Printed in the United States of America 10 9 8 7 6 5 4 3 2 1

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http://www.copyright.com
http://www.wiley.com/go/permissions
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OTHER JOHN WILEY & SONS, INC. DATABASE BOOKS BY MARK L. GILLENSON

Strategic Planning, Systems Analysis, and Database Design (with Robert Goldberg), 1984

DATABASE Step-by-Step 1st edition, 1985 2nd edition, 1990

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To my mother Sunny’s memory

and to my favorite mother-in-law, Moo

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BRIEF CONTENTS

Preface xiii

About The Author xvii

CHAPTER 1 DATA: THE NEW CORPORATE RESOURCE 1 CHAPTER 2 DATA MODELING 19 CHAPTER 3 THE DATABASE MANAGEMENT SYSTEM CONCEPT 41 CHAPTER 4 RELATIONAL DATA RETRIEVAL: SQL 67 CHAPTER 5 THE RELATIONAL DATABASE MODEL: INTRODUCTION 105 CHAPTER 6 THE RELATIONAL DATABASE MODEL: ADDITIONAL CONCEPTS 137 CHAPTER 7 LOGICAL DATABASE DESIGN 157 CHAPTER 8 PHYSICAL DATABASE DESIGN 199 CHAPTER 9 OBJECT-ORIENTED DATABASE MANAGEMENT 247 CHAPTER 10 DATA ADMINISTRATION, DATABASE ADMINISTRATION, AND DATA

DICTIONARIES 269 CHAPTER 11 DATABASE CONTROL ISSUES: SECURITY, BACKUP AND RECOVERY,

CONCURRENCY 291 CHAPTER 12 CLIENT/SERVER DATABASE AND DISTRIBUTED DATABASE 315 CHAPTER 13 THE DATA WAREHOUSE 335 CHAPTER 14 DATABASES AND THE INTERNET 365

Index 385

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CONTENTS

Preface xiii About The Author xvii

CHAPTER 1 DATA: THE NEW CORPORATE RESOURCE 1

Introduction 2 The History of Data 2

The Origins of Data 2 Data Through the Ages 5 Early Data Problems Spawn Calculating Devices 7 Swamped with Data 8 Modern Data Storage Media 9

Data in Today’s Information Systems Environment 12 Using Data for Competitive Advantage 12 Problems in Storing and Accessing Data 12 Data as a Corporate Resource 13 The Database Environment 14

Summary 15

CHAPTER 2 DATA MODELING 19

Introduction 20 Binary Relationships 20

What is a Binary Relationship? 20 Cardinality 23 Modality 24 More About Many-to-Many Relationships 25

Unary Relationships 28 One-to-One Unary Relationship 28 One-to-Many Unary Relationship 29 Many-to-Many Unary Relationship 29

Ternary Relationships 31 Example: The General Hardware Company 31 Example: Good Reading Book Stores 34 Example: World Music Association 35 Example: Lucky Rent-A-Car 36 Summary 37

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viii Contents

CHAPTER 3 THE DATABASE MANAGEMENT SYSTEM CONCEPT 41

Introduction 42 Data Before Database Management 43

Records and Files 43 Basic Concepts in Storing and Retrieving Data 46

The Database Concept 48 Data as a Manageable Resource 48 Data Integration and Data Redundancy 49 Multiple Relationships 56 Data Control Issues 58 Data Independence 60

DBMS Approaches 60 Summary 63

CHAPTER 4 RELATIONAL DATA RETRIEVAL: SQL 67

Introduction 68 Data Retrieval with the SQL SELECT Command 68

Introduction to the SQL SELECT Command 68 Basic Functions 70 Built-In Functions 81 Grouping Rows 83 The Join 85 Subqueries 86 A Strategy for Writing SQL SELECT Commands 89

Example: Good Reading Book Stores 90 Example: World Music Association 92 Example: Lucky Rent-A-Car 95 Relational Query Optimizer 97

Relational DBMS Performance 97 Relational Query Optimizer Concepts 97

Summary 99

CHAPTER 5 THE RELATIONAL DATABASE MODEL: INTRODUCTION 105

Introduction 106 The Relational Database Concept 106

Relational Terminology 106 Primary and Candidate Keys 109 Foreign Keys and Binary Relationships 111

Data Retrieval from a Relational Database 124 Extracting Data from a Relation 124 The Relational Select Operator 125 The Relational Project Operator 125 Combination of the Relational Select and Project Operators 126 Extracting Data Across Multiple Relations: Data Integration 127

Example: Good Reading Book Stores 129 Example: World Music Association 130 Example: Lucky Rent-A-Car 132 Summary 132

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Contents ix

CHAPTER 6 THE RELATIONAL DATABASE MODEL: ADDITIONAL CONCEPTS 137

Introduction 138 Relational Structures for Unary and Ternary Relationships 139

Unary One-to-Many Relationships 139 Unary Many-to-Many Relationships 143 Ternary Relationships 146

Referential Integrity 150 The Referential Integrity Concept 150 Three Delete Rules 152

Summary 153

CHAPTER 7 LOGICAL DATABASE DESIGN 157

Introduction 158 Converting E-R Diagrams into Relational Tables 158

Introduction 158 Converting a Simple Entity 158 Converting Entities in Binary Relationships 160 Converting Entities in Unary Relationships 164 Converting Entities in Ternary Relationships 166 Designing the General Hardware Co. Database 166 Designing the Good Reading Bookstores Database 170 Designing the World Music Association Database 171 Designing the Lucky Rent-A-Car Database 173

The Data Normalization Process 174 Introduction to the Data Normalization Technique 175 Steps in the Data Normalization Process 177 Example: General Hardware Co. 185 Example: Good Reading Bookstores 186 Example: World Music Association 188 Example: Lucky Rent-A-Car 188

Testing Tables Converted from E-R Diagrams with Data Normalization 189 Building the Data Structure with SQL 191 Manipulating the Data with SQL 192 Summary 193

CHAPTER 8 PHYSICAL DATABASE DESIGN 199

Introduction 200 Disk Storage 202

The Need for Disk Storage 202 How Disk Storage Works 203

File Organizations and Access Methods 207 The Goal: Locating a Record 207 The Index 207 Hashed Files 215

Inputs to Physical Database Design 218 The Tables Produced by the Logical Database Design Process 219 Business Environment Requirements 219 Data Characteristics 219

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x Contents

Application Characteristics 220 Operational Requirements: Data Security, Backup, and Recovery 220

Physical Database Design Techniques 221 Adding External Features 221 Reorganizing Stored Data 224 Splitting a Table into Multiple Tables 226 Changing Attributes in a Table 227 Adding Attributes to a Table 228 Combining Tables 230 Adding New Tables 232

Example: Good Reading Book Stores 233 Example: World Music Association 234 Example: Lucky Rent-A-Car 235 Summary 237

CHAPTER 9 OBJECT-ORIENTED DATABASE MANAGEMENT 247

Introduction 248 Terminology 250 Complex Relationships 251

Generalization 251 Inheritance of Attributes 253 Operations, Inheritance of Operations, and Polymorphism 254 Aggregation 255 The General Hardware Co. Class Diagram 256 The Good Reading Bookstores Class Diagram 256 The World Music Association Class Diagram 259 The Lucky Rent-A-Vehicle Class Diagram 260

Encapsulation 260 Abstract Data Types 262 Object/Relational Database 263 Summary 264

CHAPTER 10 DATA ADMINISTRATION, DATABASE ADMINISTRATION, AND DATA DICTIONARIES 269

Introduction 270 The Advantages of Data and Database Administration 271

Data as a Shared Corporate Resource 271 Efficiency in Job Specialization 272 Operational Management of Data 273 Managing Externally Acquired Databases 273 Managing Data in the Decentralized Environment 274

The Responsibilities of Data Administration 274 Data Coordination 274 Data Planning 275 Data Standards 275 Liaison to Systems Analysts and Programmers 276 Training 276 Arbitration of Disputes and Usage Authorization 277 Documentation and Publicity 277

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Contents xi

Data’s Competitive Advantage 277 The Responsibilities of Database Administration 278

DBMS Performance Monitoring 278 DBMS Troubleshooting 278 DBMS Usage and Security Monitoring 279 Data Dictionary Operations 279 DBMS Data and Software Maintenance 280 Database Design 280

Data Dictionaries 281 Introduction 281 A Simple Example of Metadata 282 Passive and Active Data Dictionaries 284 Relational DBMS Catalogs 287 Data Repositories 287

Summary 287

CHAPTER 11 DATABASE CONTROL ISSUES: SECURITY, BACKUP AND RECOVERY, CONCURRENCY 291

Introduction 292 Data Security 293

The Importance of Data Security 293 Types of Data Security Breaches 294 Methods of Breaching Data Security 294 Types of Data Security Measures 296

Backup and Recovery 303 The Importance of Backup and Recovery 303 Backup Copies and Journals 303 Forward Recovery 304 Backward Recovery 305 Duplicate or ‘‘Mirrored’’ Databases 306 Disaster Recovery 306

Concurrency Control 308 The Importance of Concurrency Control 308 The Lost Update Problem 308 Locks and Deadlock 309 Versioning 310

Summary 311

CHAPTER 12 CLIENT/SERVER DATABASE AND DISTRIBUTED DATABASE 315

Introduction 316 Client/Server Databases 316 Distributed Database 321

The Distributed Database Concept 321 Concurrency Control in Distributed Databases 325 Distributed Joins 327 Partitioning or Fragmentation 329 Distributed Directory Management 330 Distributed DBMSs: Advantages and Disadvantages 331

Summary 332

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xii Contents

CHAPTER 13 THE DATA WAREHOUSE 335

Introduction 336 The Data Warehouse Concept 338

The Data is Subject Oriented 338 The Data is Integrated 339 The Data is Non-Volatile 339 The Data is Time Variant 339 The Data Must Be High Quality 340 The Data May Be Aggregated 340 The Data is Often Denormalized 340 The Data is Not Necessarily Absolutely Current 341

Types of Data Warehouses 341 The Enterprise Data Warehouse (EDW) 342 The Data Mart (DM) 342 Which to Choose: The EDW, the DM, or Both? 342

Designing a Data Warehouse 343 Introduction 343 General Hardware Co. Data Warehouse 344 Good Reading Bookstores Data Warehouse 348 Lucky Rent-A-Car Data Warehouse 350 What About a World Music Association Data Warehouse? 351

Building a Data Warehouse 352 Introduction 352 Data Extraction 352 Data Cleaning 354 Data Transformation 356 Data Loading 356

Using a Data Warehouse 357 On-Line Analytic Processing 357 Data Mining 357

Administering a Data Warehouse 360 Challenges in Data Warehousing 361 Summary 362

CHAPTER 14 DATABASES AND THE INTERNET 365

Introduction 366 Database Connectivity Issues 367 Expanded Set of Data Types 373 Database Control Issues 374

Performance 374 Availability 375 Scalability 376 Security and Privacy 376

Data Extraction into XML 379 Summary 381

INDEX 385

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PREFACE

PURPOSE OF THIS BOOK

A course in database management has become well established as a required course in both undergraduate and graduate management information systems degree programs. This is as it should be, considering the central position of the database field in the information systems environment. Indeed, a solid understanding of the fundamentals of database management is crucial for success in the information systems field. An IS professional should be able to talk to the users in a business setting, ask the right questions about the nature of their entities, their attributes, and the relationships among them, and quickly decide whether their existing data and database designs are properly structured or not. An IS professional should be able to design new databases with confidence that they will serve their owners and users well. An IS professional should be able to guide a company in the best use of the various database-related technologies.

Over the years, at the same time that database management has increased in importance, it has also increased tremendously in breadth. In addition to such fundamental topics as data modeling, relational database concepts, logical and physical database design, and SQL, a basic set of database topics today includes object-oriented databases, data administration, data security, distributed databases, data warehousing, and Web databases, among others. The dilemma faced by database instructors and by database books is to cover as much of this material as is reasonably possible so that students will come away with a solid background in the fundamentals without being overwhelmed by the tremendous breadth and depth of the field. Exposure to too much material in too short a time at the expense of developing a sound foundation is of no value to anyone. We believe that a one-semester course in database management should provide a firm grounding in the fundamentals of databases and provide a solid survey of the major database subfields, while deliberately not being encyclopedic in its coverage. With these goals in mind, this book:

■ Is designed to be a carefully and clearly written, friendly, narrative introduction to the subject of database management that can reasonably be completed in a one-semester course.

■ Provides a clear exposition of the fundamentals of database management while at the same time presentng a broad survey of all of the major topics of the field.

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xiv Preface

It is an applied book of important basic concepts and practical material that can be used immediately in business.

■ Makes extensive use of examples. Four major examples are used throughout the text where appropriate, plus two minicases that are included among the chapter exercises at the end of every chapter. Having multiple examples solidifies the material and helps the student not miss the point because of the peculiarities of a particular example.

■ Starts with the basics of data and file structures and then builds up in a progressive, step-by-step way through the distinguishing characteristics of database.

■ Has a story and accompanying photograph of a real company’s real use of database management at the beginning of every chapter. This is both for motivational purposes and to give the book a more practical, real-world feel.

■ Includes a chapter on SQL that concentrates on the data-retrieval aspect and applies to essentially every relational database product on the market.

NEW IN THE SECOND EDITION

It is important to reflect advances in the database management systems environment in this book as the world of information systems continues to progress. Furthermore, we want to continue adding materials for the benefit of the students who use this book. Thus we have made the following changes to the second edition.

■ A ‘‘mobile chapter’’ on data retrieval with SQL that can be covered early in the book, where it appears as Chapter 4, or later in the book after the chapters on database design. This is introduced in response to a large reviewer survey that indicated a roughly 50–50 split between instructors who like to introduce data retrieval with SQL early in their courses to engage their students in hands-on exercises as soon as possible to pique their interest and instructors who feel that data retrieval with SQL should come after database design.

■ Internet-accessible databases that match the four main examples running through the book’s chapters for hands-on student practice in data retrieval with SQL, plus additional hands-on material.

■ The conversion of the book’s entity-relationship diagrams to today’s standard practice format that is compatible with MS Visio, among other software tools.

■ The addition of examples for creating and updating databases using SQL. ■ The addition of ‘‘It’s Your Turn’’ exercises and the new formatting of the

‘‘Concepts in Action’’ real example vignettes. ■ The merging of the material about disk devices and access methods and file

organizations into the chapter on physical database design, to create a complete package on this subject in one chapter.

ORGANIZATION OF THIS BOOK

The book effectively divides into two halves. After the introduction in Chapter 1, Chapters 2 lays the foundation of data modeling. Chapter 3 describes the fundamental concepts of databases and contrasts them with ordinary files. Importantly, this is done separately from and prior to the discussion of relational databases. Chapter 4 is the ‘‘mobile chapter’’ on data retrieval with SQL that can be covered as Chapter 4

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Preface xv

or can be covered after the chapters on database design. Chapters 5 and 6 explain the major concepts of relational databases. In turn, this is done separately from and prior to the discussion of logical database design in Chapter 7 and physical database design (yes, a whole chapter on this subject) in Chapter 8. Separating out general database concepts from relational database concepts from relational database design serves to bring the student along gradually and deliberately with the goal of a solid understanding at the end.

Then, in the second half of the book, each chapter describes one or more of the major database subfields. These latter chapters are generally independent and for the most part can be approached in any order. They include Chapter 9 on object- oriented database, Chapter 10 on data administration, database administration, and data dictionaries, Chapter 11 on security, backup and recovery, and concurrency, Chapter 12 on client/server database and distributed database, Chapter 13 on the data warehouse, and Chapter 14 on database and the Internet.

SUPPLEMENTS (www.wiley.com/college/gillenson)

The Web site includes several resources designed to aid the learning process:

■ PowerPoint slides for each chapter that instructors can use as is or tailor as they wish and that students can use both to take notes on in the classroom and to help in studying at home.

■ Quizzes for each chapter that students can take on their own to test their knowledge.

■ For instructors: The Instructors’ Manual, written by the author. For each chapter it includes a guide to presenting the chapter, discussion stimulation points, and answers to every question, exercise, and minicase at the end of each chapter.

■ For instructors: The Test Bank, written by the author. Questions are organized by chapter and are designed to test the level of understanding of the chapter’s concepts, as well as such basic knowledge as the definitions of key terms presented in the chapter.

Database Software

Now available to educational institutions adopting this Wiley textbook is a free 3-year membership to the MSDN Academic Alliance. The MSDN AA is designed to provide the easiest and most inexpensive way for academic departments to make the latest Microsoft software available in labs, classrooms, and on student and instructor PCs.

Database software, including Access and SQL Server, is available through this Wiley and Microsoft publishing partnership, free of charge with the adoption of Gillenson’s textbook. (Note that schools that have already taken advantage of this opportunity through Wiley are not eligible again, and Wiley cannot offer free membership renewals.) Each copy of the software is the full version with no time limitation, and can be used indefinitely for educational purposes. Contact your Wiley sales representative for details. For more information about the MSDN AA program, go to http://msdn.microsoft.com/academic.

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xvi Preface

ACKNOWLEDGMENTS

I would like to thank the reviewers of the manuscript for their time, their efforts, and their insightful comments:

Paul Bergstein University of Massachusetts Dartmouth

Susan Bickford Tallahassee Community College

Jim Q. Chen St. Cloud State University

Shamsul Chowdhury Roosevelt University

Deloy Cole Greenville College

Terrence Fries Indiana University of Pennsylvania

Dick Grant Seminole Community College

Betsy Headrick Chattanooga State Community College

Shamim Khan Columbus State University

Barbara Klein University of Michigan—Dearborn

Karl Konsdorf Sinclair Community College

Yunkai Liu Gannon University

Margaret McClintock Mississippi University for Women

Thomas Mertz Kansas State University

Keith R. Nelms Piedmont College

Bob Nielson Dixie State College

Rachida F. Parks Pennsylvania State University

Lara Preiser-Houy California State University Pomona

Il-Yeol Song Drexel University

Brian West Univeristy of Louisiana at Lafayette

R. Alan Whitehurst Southern Virginia University

Diana Wolfe Oklahoma State University at Oklahoma City

Hong Zhou Saint Joseph College

In addition, I would like to acknowledge and thank several people who read and provided helpful comments on specific chapters and portions of the manuscript: Mark Cooper of FedEx Corp., Satish Puranam of the University of Memphis, David Tegarden of Virginia Tech, and Trent Sanders.

I would also like to thank the people and companies who agreed to participate in the Concepts in Action vignettes that appear at the beginning of each chapter and, in some cases, which appear later in the chapters. I strongly believe that business students should not have to study subjects like database management in a vacuum. Rather, they should be regularly reminded of the real ways in which real companies put these concepts and techniques to use. Whether the products involved are power tools, auto parts, toys, or books, it is important always to remember that database management supports businesses in which millions and billions of dollars are at stake every year. Thus, the people and companies who participated in these vignettes have significantly added to the educational experience that the students using this book.

Finally, I would like to thank the crew at John Wiley & Sons for their continuous support and professionalism, in particular Rachael Leblond, my editor for this edition of the book, and Beth Lang Golub, my long-time editor and friend, and her excellent staff.

Mark L. Gillenson Memphis, TN

April 2011

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ABOUT THE AUTHOR

Dr. Mark L. Gillenson has been practicing, researching, teaching, writing, and, most importantly, thinking, about data and database management for over 35 years, split between working for the IBM Corporation and being a professor in the academic world. While working for IBM he designed databases for IBM’s corporate headquarters, consulted on database issues for some of IBM’s largest customers, taught database management at the prestigious IBM Systems Research Institute in New York, and conducted database seminars throughout the United States and on four continents. In one such seminar, he taught introduction to database to an IBM development group that went on to develop one of IBM’s first relational database management system products, SQL/DS.

Dr. Gillenson conducted some of the earliest studies on data and database administration and has written extensively about that subject as well as about database design. He is an associate editor of the Journal of Database Management, with which he has been associated since its inception. This is his third book on database management, all published by John Wiley & Sons, Inc. Dr. Gillenson is currently a professor of MIS in the Fogelman College of Business and Economics of The University of Memphis. His degrees are from Rensselaer Polytechnic Institute and The Ohio State University.

Oh, and speaking of interesting kinds of data, as a graduate student Dr. Gillenson invented the world’s first computerized facial compositor and codeveloped an early computer graphics system that, among other things, was used to produce some of the special effects in the first Star Wars movie.

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C H A P T E R 1

DATA: THE NEW CORPORATE RESOURCE

T he development of database management systems, as well as the development of modern computers, came about as a result of society’s recognition of the crucial

importance of storing, managing, and retrieving its rapidly expanding volumes of business data. To understand how far we have come in this regard, it is important to know where we began and how the concept of managing data has developed. This chapter begins with the historical background of the storage and uses of data and then continues with a discussion of the importance of data to the modern corporation.

OBJECTIVES

■ Explain why humankind’s interest in data dates back to ancient times. ■ Describe how data needs have historically driven many information technology

developments. ■ Describe the evolution of data storage media during the last century. ■ Relate the idea of data as a corporate resource that can be used to gain a

competitive advantage to the development of the database management systems environment.

CHAPTER OUTLINE

Introduction The History of Data

The Origins of Data Data Through the Ages Early Data Problems Spawn

Calculating Devices Swamped with Data Modern Data Storage Media

Data in Today’s Information Systems Environment

Using Data for Competitive Advantage

Problems in Storing and Accessing Data

Data as a Corporate Resource The Database Environment

Summary

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2 C h a p t e r 1 Data: The New Corporate Resource

INTRODUCTION

What a fascinating world we live in today! Technological advances are all around us in virtually every aspect of our daily lives. From cellular telephones to satellite television to advanced aircraft to modern medicine to computers—especially computers—high tech is with us wherever we look. Businesses of every description and size rely on computers and the information systems they support to a degree that would have been unimaginable just a few short years ago. Businesses routinely use automated manufacturing and inventory-control techniques, automated financial transaction procedures, and high-tech marketing tools. As consumers, we take for granted being able to call our banks, insurance companies, and department stores to instantly get up-to-the-minute information on our accounts. And everyone, businesses and consumers alike, has come to rely on the Internet for instant worldwide communications. Beneath the surface, the foundation for all of this activity is data: the stored facts that we need to manage all of our human endeavors.

This book is about data. It’s about how to think about data in a highly organized and deliberate way. It’s about how to store data efficiently and how to retrieve it effectively. It’s about ways of managing data so that the exact data that we need will be there when we need it. It’s about the concept of assembling data into a highly organized collection called a ‘‘database’’ and about the sophisticated software known as a ‘‘database management system’’ that controls the database and oversees the database environment. It’s about the various approaches people have taken to database management and about the roles people have assumed in the database environment. We will see many real-world examples of data usage throughout this book.

Computers came into existence because we needed help in processing and using the massive amounts of data we have been accumulating. Is the converse true? Could data exist without computers? The answer to this question is a resounding ‘‘yes.’’ In fact, data has existed for thousands of years in some very interesting, if by today’s standards crude, forms. Furthermore, some very key points in the history of the development of computing devices were driven, not by any inspiration about computing for computing’s sake, but by a real need to efficiently handle a pesky data management problem. Let’s begin by tracing some of these historical milestones in the evolution of data and data management.