Re: Detecting changes to certain fields in 'before update' trigger functions - Mailing list pgsql-general

From Sebastian Tennant
Subject Re: Detecting changes to certain fields in 'before update' trigger functions
Date
Msg-id 4p1nkg4n.fsf@vps203.linuxvps.org
Whole thread Raw
In response to Detecting changes to certain fields in 'before update' trigger functions  (Sebastian Tennant <sebyte@smolny.plus.com>)
Responses Re: Detecting changes to certain fields in 'before update' trigger functions
Re: Detecting changes to certain fields in 'before update' trigger functions
List pgsql-general
Quoth "Richard Broersma" <richard.broersma@gmail.com>:
> On Mon, Dec 1, 2008 at 7:18 AM, Sebastian Tennant
> <sebyte@smolny.plus.com> wrote:
>
>>  IF (NEW.<column-name> != OLD.<column-name>) THEN ...
>
>  The != operator doesn't work the way you might think when nulls are
> thrown into the mix.  I asked a similar question a while back and was
> kindly pointed to the following syntax:
>
> IF( NEW.* IS DISTINCT FROM OLD.* ) THEN ...

That's it!  Thanks very much Richard.

I sometimes think this kind of gotcha is purposely buried, or not
addressed at all, in order to force users to read the manual.  I wasn't
planning on spending four hours doing just that, but now I suppose I'm
almost glad I did.

Sebastian

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