Subject | AW: [Firebird-Java] Re: delete with null not executed |
---|---|
Author | Steffen Heil |
Post date | 2009-01-20T15:27:13Z |
> > Issue is that NULL=NULL -> false and this is according to the SQLOnly if you abuse NULL.
> > standard.
>
> y, i always forgot about that...it sounds like a bad choice... at
> least based on my experience...
NULL does not mean "no such thing", but "unknown".
Therefore, if you want to specify, that something is not existant, you need
to set a special value for this.
If you compare NULL=NULL, however, you want to know, if two things - that
you do not know at all - are equal. This is undecideable. Therefor NULL=NULL
returns false as well as NULL<>NULL returns false.
Regards,
Steffen
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