For seasoned developers, this could be the book that you wish you'd had when you started out building web database apps and data-driven sites. Keeping a copy around for reference, especially if you frequently jump back and forth between projects in different languages/environments, also might be helpful - for those occasions when you need of a quick refresher in PHP/MySQL dev. Moreover, if you find yourself in the position of having to mentor junior developers (or helping non-coder friends) tasked with building or maintaining PHP/MySQL-based sites or apps, then lending them your copy or recommending that they buy their own could save you quite a bit of time and frustration.