From: | Alban Hertroys <alban(at)magproductions(dot)nl> |
---|---|
To: | Michael Glaesemann <grzm(at)myrealbox(dot)com> |
Cc: | CSN <cool_screen_name90001(at)yahoo(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: NULL != text ? |
Date: | 2005-10-20 10:10:17 |
Message-ID: | 43576D09.9090305@magproductions.nl |
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Lists: | pgsql-general |
Michael Glaesemann wrote:
> if (OLD.value IS NOT NULL and NEW.value IS NOT NULL and OLD.value <>
> NEW.value) or OLD.value IS NULL or NEW.value IS NULL
>
> But that's untested and I have a hard time thinking in three-value logic.
For completeness sake; Because of lazy evaluation, that boils down to:
if (OLD.value IS NULL OR NEW.value IS NULL OR OLD.value <> NEW.value)
The last part of the expression is only evaluated if both OLD.value and
NEW.value aren't NULL.
--
Alban Hertroys
alban(at)magproductions(dot)nl
magproductions b.v.
T: ++31(0)534346874
F: ++31(0)534346876
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