I know it sounds stupid, but start out with reading PHP and MySQL for Dummies by Janet Valade ($24.95 USD)...It's written in Plain English, and if you have no prior experiance, it does a WORLD of good...I'm about 1/2 way through myself, and I have a MUCH greater understanding of MySQL and SQL in general...
I highly recommend it as a fast and easy way to get started, but nothing teaches like good ol' experiance