Comment Re:Dammit (Score 1) 208
Well comments and replies naturally lend themselves to a tree, and the obvious way to store them is by using some self-referential parentid to the same table. In practice this becomes difficult for exactly the reason you cited, no recursion. But recursion is hard to optimize for a database which is why I presume it's not built in to SQL, but the answer for modeling trees in SQL is to use nested sets which allow you to extract parts of a tree and determine the depth at the same time, it's a very fast operation because you are simply selecting a range of numbers which databases are very good at.
