This is quite simply, the best computer book I've ever read, and the book I wish I'd had ten years ago when I was just starting with websites. It explains PHP and MySQL and how to create even large and complicated websites clearly and concisely. Its examples are well chosen for both their practical uses and how they illustrate the concepts at hand and explained with just about the right mixture of code and explanation, but it doesn't limit itself to just that.
It doesn't really ever bog itself down in the minutiae, but stays clear on covering the concepts. For some, this might be a weakness because it doesn't walk you by the hand through every single function php has, but personally I'd rather use the manual for the details and was rather hoping for something that explained as the more complicated concepts behind how to use the functions, which precisely this does.
It also handles concepts like security, how to organize code, and what you should want out of a website, whether you're programming brochureware or a technically innovative ecommerce site. Which strictly might not fall directly under PHP or MySQL, but considering the audience for this type of book, is some damn useful information. I'm relatively experienced, but I still feel that I learned a lot from this book, and am recommending it to some friends who have been making noises about learning to program some basic websites as the best starter book once you know some HTML.