monline

Tom has written a pretty nice article on how to avoid the (in)famous "ORA-04091 table xy is mutating, trigger/function may not see it" errors. It's worth to read if you don't know the answer by yourself.

I came upon this article by searching on the net for the conditions where you cannot/mustn't query the parent table in a trigger (I always forget that you can do this only in "before insert" row level triggers ... or in statement level triggers of course).