A SANE APPROACH TO DATABASE DESIGN

By Mark Johansen

Reviewer: Rod Clark

Every business has streams of important data that have to be managed in a comprehensive way in order to get the most value out of them. To manage these streams you need to build one or more databases. It’s common knowledge that knowing SQL, or structured query language, is a requisite for building data bases—and there is plenty of literature available on that subject (one of my favorites is the SQL Bible, John Wiley & Sons, Inc., 2003), but as author Mark Johansen explains in A Sane Approach to Database Design , there’s a lot more to database design than SQL. After all, SQL is simply a language designed to convey a subject, but first you need to frame the subject you wish to convey. “The purpose of database design is to create an informational model of the subject that we want to build a computer system for,” Johansen explains.

The real challenge of building a well functioning data base is to translate real requirements into an informational model that can be used in conjunction with a relational database. The basic principles of designing a good database are the same, Johansen explains, regardless of which data base software you employ.

Of course a database is not reality—it’s an informational model of reality, so Johansen begins, reasonably enough, with a discussion of models and their development. What are the pieces of a good model? What does one look like? How does it evolve? How do you structure a database to reduce complexity and avoid redundancy? The author is a programmer as well as a database designer, but he stresses that it is easier to repair a poorly written program than to fix a poor design. Hence it is better to do it right from the beginning: ab ovo—from the egg.

From this foundation, Johansen guides the reader through a comprehensive and intelligently sequential discussion of every aspect of building a database: working with SQL, defining terminology, describing entities, developing relationships, working with attributes , keys—and the challenges involved with naming these elements and using terminology appropriate to the users’ organization. The text is enriched with many detailed examples, illustrations, and flowcharts.