Message-ID: <005801c464dd$72b5bec0$0403a8c0@fejleszt4>
From: =?ISO-8859-1?Q?SZUCS_G=E1bor?= <surrano@mailbox.hu>
To: <pgsql-sql@postgresql.org>
References: 
 <77ED2BF75D59D1439F90412CC5B109740E8A2E38@ie10-sahara.hiso.honeywell.com>
	<40EBD891.3050205@archonet.com>
Subject: Re: Triggers - need help !!!
Date: Thu, 8 Jul 2004 13:19:28 +0200
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I'd like to add that a NULL value might mess things up. If CreateTime may be
null, try this:

  if (OLD.CreateTime <> NEW.CreateTime) OR
     (OLD.CreateTime ISNULL <> NEW.CreateTime ISNULL) THEN ...

or this:

  if COALESCE(OLD.CreateTime, '3001-01-01') <>
     COALESCE(NEW.CreateTime, '3001-01-01') THEN ...

(provided you can safely assume that createtimes remain in this millenium
;) )

or maybe:

  if COALESCE(OLD.CreateTime <> NEW.CreateTime,
              OLD.CreateTime ISNULL <> NEW.CreateTime ISNULL) THEN ...

However; I'd stay with the first one. It's quite simple and Y3K-safe ;)
Also, it seems to be the most effective of them, if any.

G.
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----- Original Message ----- 
From: "Richard Huxton" <dev@archonet.com>
Sent: Wednesday, July 07, 2004 1:03 PM


> Pradeepkumar, Pyatalo (IE10) wrote:
> > Thanks a lot for ur help.
> >  In the trigger, I am checking if a field is updated or not. The syntax
I
> > use is
> >
> > IF UPDATE(CreateTime) THEN
> > ....
> > ....
> > END IF;
> >
> > Is this syntax correct.
>
> No, and I don't recall seeing anything like it in the manuals.
>
> IF OLD.CreateTime <> NEW.CreateTime THEN
>   ...