Getting multible variable out of mysql

first time Stackoverflower here! :)

I have a problem, and i have no idea how to even begin trying to solve it. I'm making a music-site where bands can sign up. In this process they pick a Main genre and then they pick multible subgenres in a checkbox. an example could be: Name: Tool, Main: Rock, Subgenre: Alternative Rock, Art rock, Progressive Rock.

So here is my question: I have a place on the site where only bands with surtain subgenre can acces. So let's say that its a place where only Art Rock bands can enter. How do i make the single tablerow called subgenre give me multible variables i can check to see if one of them is: Artrock.