Re: Idempotence and "Replication Insensitivity" are equivalent ?

vc wrote:
> According to ANSI SQL, nulls are ignored in the aggregate functions
> (except count(*)). It may not make sense to you, but it makes sense
> to a lot of other folks.

Or yeah, those folks defined null as a neutral element for sum aggregate too. Apparently they are unaware of identity:

0 + 0 + ... = 0

> > It is obvious that you are after neutral elements -oo and +oo such that
> >
> > MIN(d, -oo) = -oo
> > MAX(d, -oo) = d
> > MIN(d, +oo) = d
> > MAX(d, +oo) = +oo
>
> What's +oo in, say, the set of integers ?

What I'm saying is that you have to define different neutral elements for different aggregates in order to maintain elementary consistency. A little imagination on the interpretation of +infinity and -infinity elements in the domain of computer number representations may help. Received on Sat Sep 23 2006 - 01:58:38 CEST