sql query recursive exclude forums

[Mooff]

I know how to write it by hand. But that's not want i want. It has to be automated since we will add a lot of boards in those categories over the time (and it does affect more than 50 subforums as of right now - i didn't count).

So i'm looking for a vb-function which allready does what i want. There should be something in the search? Where one can search through a whole category.