I have just started learning some PHP & MySQL development using "PHP & MySQL Web Development" published by Sams and "Web Database Applications with PHP & MySQL" from O'Reilly. Prospective readers might be wondering the difference between the two in deciding which one to buy, so I hope to shed some light on the issue.
Sams: The Welling and Thomson book is more "hands-on" in that it takes the reader step-by-step in developing an e-commerce website. The chapters are organized in a goal-oriented manner: PHP, MySQL, the basics of e-commerce, security, and design of the site.
If I had to choose just one book, I would go with the Sams book due to its more gentle learning curve. However, I believe that the O'Reilly book is no slouch, and I will probably come to appreciate it more once I gain more experience in PHP and MySQL development.
I highly recommend both books to prospective PHP and MySQL developers who are willing to spend some time and effort.