What I mean by that is that the Internet, although a great source of info, is no where near as useful as a good old fashioned book when it comes to learning PHP.
I could be wrong but it sounds to me like you've probably been trying to learn PHP/MySQL by surfing the Net.
For anyone to attempt to learn PHP/MySQL from surfing the Net is a bold and impressive challenge, but as a learning strategy that type of approach is fundamentally flawed.