SQL and Relational Theory, 2nd Edition

THE RELATIONAL MODEL IS MUCH MISUNDERSTOOD

Professionals in any discipline need to know the foundations of their field. So if you’re a database professional, you need to know the relational model, because the relational model is the foundation (or a large part of the foundation, at any rate) of the database field in particular. Now, every course in database management, be it academic or commercial, does at least pay lip service to the idea of teaching the relational model—but most of that teaching seems to be done very badly, if results are anything to go by. Certainly the model isn’t well understood in the database community at large. Here are some possible reasons for this state of affairs:

• The model is taught in a vacuum. That is, for beginners at least, it’s hard to see the relevance of the material, or it’s hard to understand the problems it’s meant to solve, or both.

• The instructors themselves don’t fully understand or appreciate the significance of the material.

• Perhaps most likely in practice, the model as such isn’t taught at all—the SQL language, or some specific dialect of that language, such as the Oracle dialect, is taught instead.

So this book is aimed at database practitioners in general, and SQL practitioners in particular, who have had some exposure to the relational model but don’t know as much about it as they ought to, or would like to. It’s definitely not meant for beginners; however, it isn’t just a refresher course, either. To be more specific, I’m sure you know ...