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

From: vc <boston103_at_hotmail.com>
Date: 8 Dec 2005 20:11:24 -0800
Message-ID: <1134101484.507023.143250@g43g2000cwa.googlegroups.com>

JOG wrote:
> 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?

I am not sure what point you are trying to make. Are you suggesting that nulls be allowed in , say, Boolean columns ? Or just the opposite ?

> In a world where the equality relation over a logical domain is not reflexive?!? This whole
> argument makes no sense to me.

Whose argument are you objecting to ?

>. 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!).

What's that supposed to mean ?

>
> All best, Jim.
Received on Thu Dec 08 2005 - 22:11:24 CST