Re: So what's null then if it's not nothing?
Date: Tue, 29 Nov 2005 09:27:13 +0100
In article <1133232777.740200.225290_at_g14g2000cwa.googlegroups.com>,
> michael_at_preece.net wrote:
> > vc wrote:
> > > So you insist that the valuation of "null=null" as true can make sense
> > > in some cases ? If so, what are those cases ?
> > "X3H2-92-154/DBL CBR-002
> > 3.1 Definitions
> > h) distinct: Two values are said to be not distinct if either:
> > both are the null value, or they compare equal according to
> > Subclause 8.2, "<comparison predicate>". Otherwise they are
> > distinct. Two rows (or partial rows) are distinct if at
> > least
> > one of their pairs of respective values is distinct.
> > Otherwise
> > they are not distinct. The result of evaluating whether or
> > not
> > two values or two rows are distinct is never unknown."
> You are confused, amigo.
> Whether or not two values are considered distinct is irrelevant to the
> null = null comparison.
By SQL fiat, perhaps. But *should* it be? What gives SQL the right to redefine notions of equality and "distinctness" in this manner? Or never mind the right; does it make *sense*? Is it worth the price?
By the way, is NULL = NULL a valid SQL expression now?
Received on Tue Nov 29 2005 - 09:27:13 CET