using LIKE is not the way to go either, because there is no guarantee of _ after each prefix... yes, i always DO use _, but it's not forced upon the admin at setup..
I know it's not guaranteed. But doesn't escaping the _ with a \ make sure you test for ubbt_ instead of ubbt?. Don't see why like can't do the trick we want.
this should also handle the _ problem you had..

well, it definatly saves adding code to escape the _.