Re: Checking inequality

COALESCE is good enough for me. Thanks.

On Sat, 11 Dec 2004 09:33:32 -0700, Michael Fuhr <mike(at)fuhr(dot)org> wrote:
> On Sat, Dec 11, 2004 at 02:42:21PM +0200, Vitaly Belman wrote:
>
> > IF old.series_id<>new.series_id THEN
> > ...
> > The problem is that series_id can change to be NULL in which case I
> > have problems as "NULL <> 7" doesn't return "true".
> >
> > What can I do to check inequality even in the case that old or new
> > series_id is NULL? I'd prefer not to do zillion silly comparisons
> > (like "IS NULL and IS NOT NULL"). Is there an easy way?
>
> You could COALESCE the fields to a value that would normally be
> invalid:
>
> IF COALESCE(old.series_id, -1) <> COALESCE(new.series_id, -1) THEN
>
> This assumes that you'd want two NULLs to compare as equal.
>
> You could also use CREATE OPERATOR to create an operator that
> behaves as you'd like. This has been discussed recently; see
> the list archives.
>
> --
> Michael Fuhr
> http://www.fuhr.org/~mfuhr/
>

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