SQL book recommendations?

[Julie Castelluzzo]

Greetings!

I was at the bookstore today browsing the books on SQL (not SQL Server),
and there were only a few to look at. I need some recommendations on a
book to purchase.

If any of you have books on SQL - Structured Query Language - that
you found particularly useful, please let me know. I'm not looking for
something of the Learn-It-ASAP genre, but something in depth that could be
used as a reference. 

Thanks.

Julie

Julie Castelluzzo          juliec at cooper.edu
Electronic Services Librarian
The Cooper Union Library   www.cooper.edu/facilities/library/library.html