| From: | Baldur Norddahl <bbn-pgsql(dot)general(at)clansoft(dot)dk> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: why the need for is null? |
| Date: | 2004-01-01 22:53:29 |
| Message-ID: | 1072997609.3ff4a4e90800a@localhost |
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| Thread: | |
| Lists: | pgsql-general |
Quoting Martijn van Oosterhout <kleptog(at)svana(dot)org>:
> Because in trivalued logic, <anything> = NULL is also NULL. You need a
> special operator to check if something is NULL, hence IS NULL and IS NOT
> NULL. SQL standard says so.
>
> This is a FAQ but I don't see it mentioned there.
Ok, but since this can be quite annoying and unexpected, could we get an
operator that does not use tristate logic but simply compares? Maybe == which
seems to be free :-)
So X==Y is true if X and Y are equal or both are null, false othervise.
Baldur
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