Can somebody explain to me how IPB does this:

The categories and forums are in the same table, and it selects them at the same time in one query, but how can it cycle through the forums and categories and tell what is the parent of what? If I need to give more details, please tell me because I am wondering how it does it.

IPB actually grabs the categories and such all at once.
Stores them in an array, and then parses them with foreach.

Thats the basic idea behind it anyways.

Chad

There is a parent row in the forums table.