On Sunday 16 March 2008 5:36 pm, Bob Pawley wrote: > Would it be possible to get an example of such coding?? > > Bob > > > ----- Original Message ----- > From: "Adrian Klaver" <aklaver@xxxxxxxxxxx> > To: <pgsql-general@xxxxxxxxxxxxxx> > Cc: "Bob Pawley" <rjpawley@xxxxxxx> > Sent: Sunday, March 16, 2008 5:14 PM > Subject: Re: Updating > > > On Sunday 16 March 2008 3:32 pm, Bob Pawley wrote: > >> Is there a method available for triggering a function after an update on > >> a > >> particular column in a table? > >> > >> The only way that I have found is to trigger after an update on the > >> whole table, which of course can lead to problems. > >> > >> Bob > > > > I trigger can be constrained to fire for each row. Inside the trigger > > function > > you can test to see if the column in question has been updated and do the > > appropriate thing. If the column has not been changed do nothing and > > RETURN > > NEW which makes the function non-op. > > -- > > Adrian Klaver > > aklaver@xxxxxxxxxxx > > > > -- > > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > > To make changes to your subscription: > > http://www.postgresql.org/mailpref/pgsql-general CREATE FUNCTION foo() RETURNS trigger AS $Body$ BEGIN IF NEW.colname != OLD.colname THEN ..."Do something"..; RETURN whatever; ELSE RETURN NEW: END IF; END; $Body$ LANGUAGE plpgsql; CREATE TRIGGER foo_test BEFORE UPDATE ON foo_table FOR EACH ROW EXECUTE PROCEDURE foo(); -- Adrian Klaver aklaver@xxxxxxxxxxx -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
