Re: So what's null then if it's not nothing?

vc wrote:
> Jon Heggland wrote:
> > In article <1134052742.347560.142840_at_o13g2000cwo.googlegroups.com>,
> > boston103_at_hotmail.com says...
> > >
> > > > I don't think a "regular" unknown/missing SQL NULL for a 2VL boolean
> > > > domain should be regarded a truth value. That would be inconsistent with
> > > > how NULL works in other domains.
> > >
> > > Then the logic ceases to be such if its truth values set include a
> > > value for which the equality predicate evaluates to anything other than
> > > TRUE or FALSE as I said elsewere.
> >
> > It does *not* include such a value. NULL is not a truth value any more
> > than it is a number or a string.
>
> I am missing something. If you store/use NULL as a logical value, haw
> can it *not* belong to the logical vaue domain with its logical
> operations? Sorry, but that does not make sense.
[snip]

But Null can never _be_ a logical value: it is by definition an indicator of the very absence of a logical value. In addition, as a logical value how could it possibly exist? In a world where the equality relation over a logical domain is not reflexive?!? This whole argument makes no sense to me. If you want to use nulls, well mathematically your looking at a meta-language, and you simply can not condense it all down into a single conceptual level (Or hofstadter might point out that you have to pass it up to the next djinn!).

All best, Jim. Received on Fri Dec 09 2005 - 02:50:58 CET