If you do buy a book, consider an e-book edition since it probably will be more current and more-easily updated. (They also
weigh a lot less!)
Also:
"Use the Source, Luke!"
Get thee out to "github" or somewhere where there is the actual complete source-code of some production-ready web site that uses PHP, MySQL and various other things, and which has installation instructions. First, study the entire source-code of the thing: pass it in front of your eyes even if you do not understand (and, you won't ...) everything that you see.
Look also far-and-wide for online web sites. Much of the professional-education material that's being produced today is being put out on web-sites, sometimes by subscription.
I suggest keeping a daily diary ... in a loose-leaf notebook with a number-two pencil.
Write down what you have learned. And, when you have a question,
write it down too. Once you've done that, it's like pinning the sucker to a display-board: it won't fly away now, so in the meantime you can "let it go" and move along. Later on, the light-bulb will pop on, and you can go back and lightly cross-off that paticular question, writing down the answer and where-and-when you found it. This keeps you from "chasing after every white-rabbit (and, red herring) that happens to come wandering by."