Case Method: Entity Relationship Modelling

Now data analysts, strategists and data administrators can learn the powerful technique of entity relationship modelling from this definitive guide. In a lucid instructional style, Richard Barker shows how the data modelling technique can be applied to develop high-quality, integrated information systems. Special features of the book include:

• a wealth of realistic examples illustrating the technique in practice
• detailed appendices highlighting the key topics including data normalization, CASE tool support, data administration and database design
• a definitive glossary of all important terms.

It is designed to be equally valuable as a training aid and as a 'hot- line' reference when problems require urgent resolution.

0201416964B04062001

Praise For Case Method: Entity Relationship Modelling

Quotes of Note"It was a pleasure to write the Foreword for such a well-written, informative book (Case Method: Entity Relationship Modelling), I learned some new guidelines for entity relationship modelling when I read it over."

Preface

Purpose

I believe that a sound grasp of entity relationship modelling can provide a firm architectural framework for understanding a business and creating flexible systems for the future. There are, however, many things that need to be considered over a period of time to take advantage of these basic techniques.

Not least of these considerations is understanding the meaning of words as applied by our users and separately within the Information Systems department. It is certainly my experience that many system developments fail because of the use of jargon and protectionism within the ivory tower of the Information Systems department, coupled with the bewildering explosion of technology. In this book I am implicitly recommending that analysts must discard their egos, and instead recognize that there is strength in their Human fallibility. In practical terms it means seeking out the most thorough and accurate understanding of the business, and then exposing that to your users and peers so they can help you gain even more accuracy. I have seen this 'egoless' team approach not only enable teams to build far more appropriate systems but act as a catalyst, knitting together users, system development staff and even accountants.

How to Use This Book

The appendices are designed to cover other useful concepts, further detail quality checks, first-cut database design and data administration. All the important terms in the book are covered by the glossary and, finally, an extensive index and the contents list are there to provide alternative entry points to the information in the book.

This book should provide 'hot-line' support to your entity relationship modelling when that really key problem requires urgent resolution.

Acknowledgments

Ensuring that the book itself is complete, consistent and coherent was a tedious but worthwhile task. I would like to thank my close colleagues who took the time to expose ambiguities, difficulty in understanding, errors and omissions. In particular I would like to say a special thank you to Barbara, my wife, with whom I have worked weekends and into the early hours whilst we struggled with definitions, style, diagrams and terminology.

Richard Barker
July, 1989

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Table of Contents

Foreword


Preface



1. Introduction

Objectives of Entity Modelling * Generic Models * Why is Entity
Relationship Modelling Important? * Your Challenge * Ten Key Issues



2. A Simple Example

The Example-Tickets for Airlines * Database Implementation * So What
Have We Found?



3. Basic Conventions and Definitions

Entity * Entity Rules * Business Relationship * Attribute * Attribute
Rules * Unique Identifier * Type and Instance * Layout Rules



4. A Second Example

The Example * Credit Card Solution * Conclusion



5. Identifying Entities, Attributes and Relationships

Identifying Entities * Identifying Attributes * Identifying
Relationships * Summary



6. A Complex Example

Atlantis Island Flights *Model the Open Ticket * Function Example * User
Presentation * So What Have We Found?



7. Advanced Conventions and Definitions

Entity * Relationships * Domain * Attribute * Summary



8. Classical Structures and Generic Patterns

Hierarchies * Networks * Changes Over Time * Bill of Materials *
Classification and Categories * Entity Types * Specific Examples *
Generic Patterns * A Word of Warning



9. Related Concepts

Dataflow and Datastore * Business Function/Process * Business Event *
Schema Architecture * External Schema * Entity Life-cycle



10. Quality and Completeness Checks

Peer Group Check * User Approval * Rules * Quality of Entities * Quality
of Attributes * Quality of Relationships * Completeness Check * Summary



11. Presentation to Senior Management

Management Direction * Summary Diagrams * Summary



Appendices


Appendix A. Data Normalization

The Purpose * Entity Modelling * Normalization * Intuitive Normalization
* Terminology * Mathematical Definitions * Beyond 3NF with Entity
Relationship Modelling * Data Denormalization



Appendix B. Valid Relationships

Many to One * One to One * Many to Many * Recursive Relationships



Appendix C. Detailed Definitions of Entity, Relationship, Domain and
Attribute

Entity Definition * Relationship Definition * Domain Definition *
Attribute Definition



Appendix D. Use of CASE Tools

Case Support For the Business System Life Cycle * Strategy Stage *
Analysis Stage * Summary



Appendix E. Data Administration

Data Administration-The Role * Control * A Key Role



Appendix F. Relational Database Design

Simple Database Design * Alternative Entity Models and their Impact on
Design * Derived Attributes * Next Steps



Appendix G. Business View

Business View * Business Functions * Data Dependence * Summary



Appendix H. Meta Model

What is a Meta Model?



Appendix I. Atlantis Island Flights-Full Model



Glossary



Index