Posted by Hugo Kornelis on 10/15/05 00:59

On Fri, 14 Oct 2005 21:51:02 +0000 (UTC), Erland Sommarskog wrote:

(snip)
>Keep in mind that you cannot just say:
>
> SELECT ...
> FROM tbl a
> JOIN audit_tbl b ON a.keycol = b.keycol
> WHERE a.col1 <> b.col1
> AND a.col2 <> b.col2
> ...
>
>Correct is:
>
> WHERE (a.col1 <> b.col1 OR
> a.col1 IS NULL AND b.col1 IS NOT NULL OR
> a.col1 IS NOT NULL AND b.col1 IS NULL)
> AND

Hi Erland,

This can be (slightly) simplified to

WHERE (NULLIF (a.col1, b.col1) IS NOT NULL OR
NULLIF (b.col1, a.col1) IS NOT NULL)
AND


Best, Hugo
--

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