I rarely read programming books, and even more infrequently have anything nice to say about them. But I found this book to be a great list of recipes, suggestions, and insider's tips for writing good SQL (Standard Query Language -- the language you use to talk to relational databases).
Paul Dubois is a notable expert in the field anyway. If I recall correctly, he's the documentation lead for the MySQL project. Thus, he's certainly well qualified to write something like this.
The tips (or most of them, at least) are highly readable, often practical, and are accompanied with illuminating text (not to be confused with ILLUMINATED text, which would certainly be a first in the programming world).
One thing was noticeably absent, though: tips on tuning queries. Dear Paul Dubois: If you ever read this, please add a section on tuning queries, using EXPLAIN, and improving overall DB performance.