I suspect you will find that triggers are aargh in any database.

Oracle has 2 types of triggers - ROW triggers and TABLE triggers. In a row trigger you can update the row that caused the trigger to fire (e.g timestamp) but you cannot query the table being updated. In a table trigger you can query the table being updated but you cannot update the row that caused the trigger to fire. In either case, they cascade through. As a result, it is almost (but not totally) impossible to do anything :(