Does anyone know of a way to change the query that is performed by the search form? Can't find the mysql code anywhere.

I would like to know if there's any way (by changing the code I'm guessing) to hide certain categories from the category view. I'm creating a menu item to link to this category.

I'm not sure how the component was programmed, but why is it that I cant see ANY mysql in the files?
I was thinking that possibly by changing the mysql query I could exclude certain catid values, but I can't even find the mysql code.