Re: Trigger to identify which column(s) updated

From: "Vishal Kashyap (at) [Sai Hertz And Control Systems]" <sank89(at)sancharnet(dot)in>
To: Jack Kerkhof <jack(dot)kerkhof(at)guest-tek(dot)com>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: Trigger to identify which column(s) updated
Date: 2004-01-18 22:29:00
Message-ID: 400B08AC.8040607@sancharnet.in
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Dear Jack ,

>I suspect that the function would look something like;
>
>CREATE FUNCTION FIND_CHANGED_COLUMNS() RETURNS OPAQUE AS '
>BEGIN
>
> -- FOR EACH COLUMN IN THE RECORD:
> -- IF ( NEW COLUMNx <> OLD COLUMNx)
> -- LOG THE RECORD PRIMARY KEY, COLUMN NAME, OLD VALUE
>
> RETURN NEW;
>END;
>' LANGUAGE 'plpgsql';
>
>

Instead of using a trigger use a rule as
<code>

</code>
CREATE RULE log_allthat AS ON UPDATE TO table_to_scan WHERE
((NEW.coloum_1 != old.NEW.coloum_1) OR (NEW.coloum_2 !=
old.NEW.coloum_2)) OR (MORE COLUMNS DO

INSERT INTO log_changes_table (

PRIMARY_KEY,COLUMN_NAME,OLD_VALUE

) VALUES (

OLD.PRIMARY_KEY,OLD.COLUMN_NAME,OLD.OLD_VALUE

);

Yes you will have to create a table as log_changes_table or any name you
fancy such that data could be loged
</code>

Kindly shoot back if this helps.

--
Regards,
Vishal Kashyap

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