I have been helping students understand relational database query languages for many years. Over these years, numerous students at the beginning of the semester have commented that they already knew some SQL from working in industry. During the semester, the students weren't sure how the coverage of relational algebra and relational calculus query languages would help them understand SQL. However, once SQL was presented in terms of the mathematical foundations of these languages, they understood - not only SQL but the relationship between SQL and the formal query languages. This recurrent anecdote provided the motivation to write this book.

Before delving into the query languages, I've included an introductory chapter on the relational data model and how to design a relational database schema using the well-known Entity-Relationship (ER) graphical data model. This introductory chapter also describes the EMPLOYEE TRAINING enterprise used as a working example throughout the book. Once the query languages are presented (a chapter is devoted to each language), a case studies chapter provides a description of three database enterprises: WEB PAGE, NEW HOME, and INVESTMENT PORTFOLIO. Each case study includes a requirements specification, its conceptual design as an ER diagram, its corresponding relational database schema, and a side-by-side comparison of the four query languages using relevant queries over the enterprise. I've also included a chapter on understanding the QBE and SQL query languages provided by the popular PC database product Microsoft Access.

The appendix describes the WinRDBI educational tool, which provides an interpreter for the relational database query languages described in the book: relational algebra, domain and tuple relational calculus, and SQL (see http://winrdbi.asu.edu). The book's companion website ( http://www.prenhall.com/dietrich ) includes the checked queries from the book so that the reader can check the results of the queries using the tool. (These queries are also available on the WinRDBI samples page.) The database and queries are provided for four database enterprises in the four query languages recognized by the tool. (An Access 2000 database for the EMPLOYEE TRAINING enterprise and queries from the book can also be found on the companion website and here.)

I've designed the book to be accessible to anyone who knows elementary set theory - from a student that is enrolled in an introductory database management course to the professional engineer that wants to learn the foundations of the industry-standard query language SQL. Readers can then apply their understanding of relational database query languages to any relational database product.

1 THE RELATIONAL DATA MODEL

1.1 Introduction

1.2 Conceptual Design

1.3 Mapping to Tables

1.4 Data Definition, Storage, and Retrieval

1.5 Summary

2 RELATIONAL ALGEBRA

2.1 Fundamental Operators

2.2 Additional Operators

2.3 Intermediate Relations and Renaming

2.4 Example Queries

2.5 Query Optimization

2.6 Summary

3 DOMAIN RELATIONAL CALCULUS

3.1 Expressions

3.2 Expressive Power

3.2.1 Fundamental Operators

3.2.2 Additional Operators

3.2.3 Safety

3.3 Example Queries

3.4 By Name Syntax

3.5 Summary

4 TUPLE RELATIONAL CALCULUS

4.1 Expressions

4.2 Expressive Power

4.2.1 Fundamental Operators

4.2.2 Additional Operators

4.2.3 Safety

4.3 Example Queries

4.4 Summary

5 SQL

5.1 Basic Query Expressions

5.2 Expressive Power

5.2.1 Fundamental Operators

5.2.2 Additional Operators

5.2.3 Exists

5.2.4 Safety

5.3 Example Queries

5.4 Additional Features of the Query Language

5.4.1 Views and Renaming of Attributes

5.4.2 Sorting

5.4.3 Aggregation

5.4.4 Nested Subqueries

5.4.5 Joined Tables

5.5 Query Optimization

5.6 Beyond the Query Language

5.6.1 Data Definition Language

5.6.2 Data Manipulation Language

5.6.3 Data Control

5.7 Summary

6 CASE STUDIES

6.1 Web Page

6.2 New Home

6.3 Investment Portfolio

6.4 Summary

7 MICROSOFT ACCESS

7.1 Data Definition

7.2 Data Population

7.3 Access QBE

7.4 Access SQL

7.5 Additional Features of Access QBE

7.6 Summary

A WINRDBI

A.1 Overview

A.2 Query Languages

A.3 Implementation Overview

A.4 Summary

BIBLIOGRAPHIC NOTES

• WinRDBI Tool Home Page
• WinRDBI PowerPoint Presentation
• Employee Training in Microsoft Access 2000
• From the Author
  (on this page)
• Table of Contents
  (on this page)