Re: Triggers on columns

On Mon, Sep 07, 2009 at 07:53:01PM +0900, Itagaki Takahiro wrote:
> However, to be honest, I think standard-compliant column trigger is
> useless... I'm thinking additional extension for triggers -- if we
> want to check modifications of actual values, it could be defined
> as:
>
> CREATE TRIGGER trig BEFORE UPDATE ON tbl FOR EACH ROW
> WHEN (NEW.col <> OLD.col) EXECUTE PROCEDURE trigger_func();

That should probably read:

CREATE TRIGGER trig BEFORE UPDATE ON tbl FOR EACH ROW
WHEN (NEW.col IS DISTINCT FROM OLD.col) EXECUTE PROCEDURE trigger_func();

Cheers,
David.
--
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
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