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

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 disagree. For consistency, I'd say that any boolean expression
> > involving NULL booleans should evaluate to NULL, just like any
> > arithmetic expression involving NULL integers evaluates to NULL (at
> > least if you accept the excuse for how SUM() works:). I don't think it
> > breaks logic more than it breaks arithmetic. If you disagree, can you
> > give any examples of profound implications?
>
> See above. You cannot determine logical expression equivalence,

Sure I can. If it is my truth tables you are worried about, they don't mention NULL, just TRUE and FALSE.

> you
> have no ability to derive anything in such 'logic', what use such
> structure might have ?

I see no more problems than NULLs cause in numeric computations.

-- 
Jon