Re: how to tell if column set on update

From: nha <lyondif02(at)free(dot)fr>
To: Chester C Young <chestercyoung(at)yahoo(dot)com>
Cc: PgSQL-sql <pgsql-sql(at)postgresql(dot)org>
Subject: Re: how to tell if column set on update
Date: 2009-07-21 00:07:03
Message-ID: 4A6506A7.10809@free.fr
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Hello,

Le 20/07/09 15:19, chester c young a écrit :
> within a trigger need to know if the UPDATE statement set a column. the column might be set to the old value or a different value.
>
> (want to make sure the app is sending all necessary values)
>
> thanks
>

If the column to test is known -- e.g. column MyCol --, NEW.MyCol and
OLD.MyCol -- respectively value of MyCol after UPDATE and value of MyCol
before UPDATE -- can be compared.

I may be wrong if you are looking for the column(s) that are really
updated, not if such a column is updated or not. In this case, each
column of the target table may be tested with their respective new and
old values as well.

Regards.
--
nha / Lyon / France.

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