First of all, your questions are welcome. I just think you would benefit from knowing what kind of functionality is out there when querying a typical SQL engine.
Secondly, I recommend testing queries in an interactive tool before you put them in code, so that when things don't work you don't have to guess whether it's a problem with the query or the PHP code. With mysql, you can do this on the command line
, using a web based tool
or one of several Windows GUI tools.
If you are getting no results, a good test might be to drop your WHERE clause and see what happens without it. Sure, you will probably then get results you don't want, but if that works it's a good clue where to look for the issue.