[osrec]

I generally keep the more complex stuff in the application layer, where it's often easier to capture and change. If all the logic goes into the DB, it can be a real pain to update and maintain (especially if you're running a cluster of sharded databases, say).

Some might suggest that you take a performance hit by not using stored procs etc, but in reality it's never been a problem for my apps (the largest one has over 150k active users - https://usebx.com).