Re: Update Trigger in IDS 7.3

If one of the value being updates is null the condition evaluates to NULL itself. Please try create trigger upd_tab1 update of col2 on tab1 referencing old as pre new as post for each row when ( (pre.col2 is null and post.col2 is not null) or (pre.col2 is not null and post.col2 is null) or (pre.col2!=post.col2)) ) (insert into tab2 (col1,col2) values ('GOT' ,'IT!' )); Madan Mashalkar <madan@infogain.com> wrote in article <6tsdvm$kqe$1@news.xmission.com>... > > > Hi, > > There is a simple trigger: > create trigger upd_tab1 update of col2 on tab1 > referencing old as pre new as post > for each row when (pre.col2 != post.col2) > (insert into tab2 (col1,col2) values ('GOT' ,'IT!' ));> > Then inserting and updating a row in an empty table tab1: > > insert into tab1 (col1,col2) values('TEST',null); > update tab1 set col2 = 'NEW' where col1 = 'TEST';> > No rows are inserted in tab2. > (Interesting, if either the pre or the post value is NULL, > no rows are inserted in tab2) > > The manual states that if the 'when' evaluates to false/unknown, then > the action(insert) will not be done. > > So, does (pre.col2 != post.col2) evaluate to unknown ??? > If yes, then is it expected behaviour ? >