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.
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Alban Hertroys
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