I'm not certain I understand what you want but I think you want a website where you can track inventory of something like BOOKS, OR movies.
Unless you gett really complex, a majority of your work is actually going to involve SQL PHP will just be a means to access the SQL from the front end.
You'll be running statement likes
$genre =$_GET['Genre']
mysql_query="SELECT * FROM `BOOKS` where genre =$genre
This isn't the place to go into detail as how to do this, you need to learn basic SQL and PHP, google this stuff online. It shouldn't be very advanced stuff as this is just the sort of stuff SQL is designed for.