Yep. His books are great. I have two of 'em:
SQL For Smarties: Advanced SQL Programming, 2nd Edition
ISBN 1-55860-576-2
This is a book that really digs deep into how SQL is supposed to work.
He covers a lot of real nitty-gritty stuff and even talks about how
many vendors haven't incorporated a ton of SQL-92 features.

SQL Puzzles and Answers
ISBN 1-55860-453-7
This book is filled with puzzles from his columns over the years and
from CompuServe forums. I learned a lot from this one.

>I know, I know. I regretted that post the minute I made it :-)
>
>Isn't Joe the guy who has the SQL for Smarties column?