Outstanding explanation, Kenney.

On the recursive thing... do keep in mind that recurssion is nothing more than a loop and has the same performance impedements as a loop. In other words, it IS a form of RBAR. There are many ways to avoid the use of any type of RBAR on many things. Even when it comes to Hierarchies, there are some really good ways to precalculate the hierarchy (nested sets) and then do the lookups using set based technologies instead of RBAR.