Am Mittwoch, 27. Juli 2005 09:47 schrieb Philippe Lang: > Thanks Tom, thanks Janning, > > I found triggers very convenient to do different tasks in the database, and > these tasks go far beyond what we can do in rules, Janning. Right. There are some things that can't be done with rules. > When a line is being inserted in an order, the insert trigger automatically > inserts data in a subtable of the order line, for example. In this > subtable, there are informations regarding the "planning" of the order. > People can use the GUI to populate the order, but things won't break if the > user opens the database table directly, which can happen sometimes. Without > the trigger, an "insert function click" would have to be used each time an > order line is being added, and this is not that effective from a > user-experience point of view, I think. Or would require a lot a > client-coding. As far as i understand your example it can be done with rules, too. > Now the use of a trigger has a drawback: when you want to duplicate an > order, for example. During the duplication function, I would like to > disable the trigger, in order to make a copy of the order, order lines, and > order lines subtable data. This is much easier than keeping the trigger, > and having to delete default data it inserts in the new order. just a thought: maybe you can insert a column "copyof_id" in your tabel and mark it if you copy orders. The trigger can check NEW.copyof and quit his work if it is marked. With rules there is a nice advantage when copying: rules are not invoked by COPY command (but sometimes it is a disadvantage if you need the rule invocation) kind regards janning ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
