Hello http://www.postgres.cz/index.php/PostgreSQL_SQL_Tricks#Fast_compare_variables_NEW_and_OLD_in_trigger.27s_body
regards Pavel Stehule 2009/7/23 Willy-Bas Loos <willy...@gmail.com>: > Hi, > > My colleage Geard Troost and I found a handy way of comparing OLD and > NEW in a trigger function. > Normally this does not work (if anyone can tell me why, that'd be > great), but once you cast them to text, it does. > > Is there anything to say against this, or can i go ahead and recommend > this to everyone who wants to check if anything changed before doing > what their update triggers do? > > Cheers, > > WBL > > Here's the code: > > drop table test; > create table test (id integer primary key, value integer); > insert into test values (1,1); > insert into test values (2,1); > insert into test values (3,1); > insert into test values (4,1); > insert into test values (5,1); > insert into test values (6,1); > > create or replace function bla() returns trigger as $$ > begin > IF (NEW::TEXT = OLD::TEXT) THEN raise notice 'changed'; > END IF; > return NEW; > end > $$ > language plpgsql; > > CREATE TRIGGER test_bla BEFORE UPDATE > ON test FOR EACH ROW > EXECUTE PROCEDURE public.bla(); > > update test set value =NULL where id= 1; > update test set value =NULL where id= 1; > > -- > "Patriotism is the conviction that your country is superior to all > others because you were born in it." -- George Bernard Shaw > > -- > Sent via pgsql-general mailing list (pgsql-general@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
