Agree with meryln and all the other mild criticism of MySQLs downsides, but I found that for doing dynamic web content, it's fine, easy to use, and readily available.

So, depending on what you are doing, as far as books go, I found MySQL and Perl for the Web by Paul DuBois helpful, and if that is too heavy, try Larry Ullman's Quickstart Guide on MySQL (even has a discussion on normalization, etc.).