i think i saw a sticky thread in one of the topics that has alot of people's recommendations... but as far as I go, I started off with "PHP4 - A Beginners Guide" by McCarty, then went to visual quickstart guide's "PHP Advanced", and later ordered Wrox's "PHP Graphics Handbook" off ebay. Never actually finished reading any of the books... because I found that this forum was the best place to learn. An active forum can give you so much more than an inactive book.
For mysql, i used Sam's Teach Yourself "SQL In 10 Minutes" and i used that for reference alot when I took a MSSQL (microsoft) course last semester... and most of the queries worked fine in both databases.
But forums and online tutorials are the best way to go... besides... can you argue with free?