Re: NULLs

"Brian Selzer" <brian_at_selzer-software.com> wrote in message news:JeSdj.2231$6%.221_at_nlpi061.nbdc.sbc.com...
>
> "stevedtrm" <stevedtrm_at_hotmail.com> wrote in message
> news:a3716365-7bc4-4a75-ab58-ee7ac957c299_at_n20g2000hsh.googlegroups.com...
> >> > If everyone is clear NULLS shouldn't be used, why the debate as to
what
> >> > to do about them ?
> >>
> >> Because SQL allows NULL and even promotes the idea that NULL solves
some
> >> problem instead of introducing many.
> >
> > So everyone is agreed that NULLs shouldn't appear anywhere, and its
> > just a matter of time before NULLS become a legacy problem and a
> > relational language supercedes SQL?
> >
>
> No, Steve, not everyone is agreed.
>
> > Are the two solutions I suggested before the widely accepted as
> > resolutions to the two problems NULLs were introduced to eradicate?
> >
> >>Missing information? Then surely there should just be no tuple?
> >
>
> A row may contain a lot more information that would otherwise be useful.
> Would you tell a potential customer that you won't serve them because you
> don't know everything about them? I think not! Haven't you been asked
for
> your e-mail address at a retailer? What would you think if the cashier
told
> you to get lost for refusing to supply it?
>
> >>To indicate that there can be no value? Why not a seperate table with
> >>a boolean value in the non-key column?
>
> In my opinion, null should only ever be used to indicate "There should be
a
> value here, but it hasn't been supplied."

A quibble.

I would say that it indicates that there is space for a value here, but no value has been place in the space.

As for the rest of it, we've had this discussion in c.d.t. before, at least a dozen times. Received on Sun Dec 30 2007 - 23:42:12 CET