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From:  Marshall <marshall.spight@gmail.com>
Newsgroups: comp.databases.theory
Subject: Re: NULLs: theoretical problems?
Date: Wed, 08 Aug 2007 18:01:15 -0000
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On Aug 8, 7:20 am, Jan Hidders <hidd...@gmail.com> wrote:
> On 8 aug, 14:26, Bob Badour <bbad...@pei.sympatico.ca> wrote:
>
> > sinister wrote:
> > > Many discussions point out one deficiency of NULLs:  that they collapse
> > > multiple, distinct concepts into one ("no value possible," "value missing,"
> > > "value not available at this time", etc).
>
> > > What are the other theoretical problems?  My impression from skimming some
> > > threads in this ng is that some anomalies might occur, maybe having to do
> > > with NULLs and joins, or NULLs and keys composed of more than one field, but
> > > I'm not sure.
>
> > The ultimate theoretical problem is a complete lack of any theory
> > underpinning NULL.
>
> Just to avoid any misunderstandings: there has of course been lots of
> theory on certain interpretations of null values, such as the work by
> Raymond Reiter and by Joachim Biskup, but not on the specific meaning
> (if you can call it that) that they were given in SQL. Whether that is
> necessarily a big problem is IMO not so easy to say.

Yes; here we run into the complete lack of any theory of whether
something is necessarily a big problem or not.


Marshall

PS. It was funnier in my head.