I happen to be enjoying the Programming the Perl DBI book. I'm almost through it now, and have found it quite helpful. However, I must say that it leaves me wanting a book focused primarily on SQL. But that doesn't mitigate the book's usefulness.

With a decent understanding of Perl, and a cursory knowledge of SQL, the book quickly brings you up to speed on how to use DBI to communicate with SQL databases. It just doesn't happen to go into real depth on SQL itself, thought it does have a good introductory chapter on the subject.

As it happens, one of the authors working on the next edition of the DBI book is a perlmonk. He's also the author of the DBD::Anydata module: Jeff Zucker. From CB discussion with him, I know that he always welcomes CB /msg's or emails with suggestions that might help to improve the next edition.