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

<michael_at_preece.net> wrote in message news:1133419048.763614.288480_at_g43g2000cwa.googlegroups.com...
>
> Jon Heggland wrote:
>
> > In article <1132912144.091433.13610_at_z14g2000cwz.googlegroups.com>,
> > michael_at_preece.net says...
> > > > Ok. Let's say that the empty string can be called "no value at all"
for
> > > > a text variable. What is "no value at all" for an integer variable?
> > > > --
> > > > Jon
> > >
> > > Well Jon - I'd say they're both NULL. NULL is type-less.
> >
> > That is a bit troublesome if you like strong typing, as I do. But let
> > that pass.
> >
>
> I'm sure the standard says NULL is type-less - or words to that effect.
> Maybe it's more along the lines of every data type must allow NULL.
>

When you started all this a couple of weeks ago, you said your head was spinning. Spinning is what I think I see here. I believe CJ Date says something along the same lines as what you just said. But I don't think that's right.

I think every CONTAINER must allow either NULL or a value from the domain. A Column is a set of CONTAINERS,
one intersecting with each row. All the CONTAINERS in a column share the same domain.

And naturally, COLUMNS that are constrained NOT NULL don't have to be able to represent NULL (Although DEC Rdb does it anyway, for the sake of symmetry, I guess) Received on Thu Dec 01 2005 - 07:49:27 CET