Re: Auto-update a field when record is changed

> On Fri, 22 Aug 2003, Stuart wrote:
>
> > Folks,
> >
> > I was wandering if there was a feasible way to automatically update a field
> > in a table, say 'revision_date' in a record whenever any other field in the
> > record is changed. My attempts to use a trigger caused repeating loops and
> > bombed with error. I would like to be able to update such a field
> > automatically anytime a record was updated. Any help would be appreciated.

Unless I'm misunderstanding you, this is really easy. Here's what
I use in nearly every database I build:

create or replace function timestamp_fn() returns opaque as '
begin
NEW.moddate = now();
return NEW;
end
' language 'plpgsql';

create table blah (
...
createdate timestamp default now(),
moddate timestamp,

create trigger blah_timestamp_tr before insert or update on blah
for each row execute procedure timestamp_fn();

Make the obvious changes for only doing this on updates.

Or am I misunderstanding your goal?

-j

--
Jamie Lawrence jal(at)jal(dot)org
"One of the great things about books is that sometimes there
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