For data modeling, I find there are few books out there that really provide good information on design best practices. After a long hard search I determined
The Data Modeling Handbook "A Best-Practices approach to Building Quality
Data Models" is one of the best books you can buy. It takes time to understand their explaination for some of their modeling practicies. I wish they gave more examples and specifics. However, once you've run into the problems they describe it becomes more clear as to why they make their recommendations.
http://www.amazon.com/exec/obidos/AS...145468-7819269
I find the date book to be a good academic book. However, it's difficult reading and requires a good background in math and set theory.
Mike