Re: NULLs

On 26 Dec, 17:47, "David Cressey" <cresse..._at_verizon.net> wrote:
> "stevedtrm" <steved..._at_hotmail.com> wrote in message
>
> news:4afba236-4273-4d24-b8f4-5041483d22fc_at_i12g2000prf.googlegroups.com...
>
> > What are NULLs for?
>
> > Missing information? Then surely there should just be no tuple?
>
> > To indicate that there can be no value? Why not a seperate table with
> > a boolean value in the non-key column?
>
> > Steve B.
>
> Go to google groups. Select the newsgroup comp.databases.theory
>
> Do a search on NULLS. You will find a multitude of discussions about NULLS.
> almost everything that this discussion might produce has been said in at
> least one of those discussions.
>
> Short answer: yes, it is to indicate that there is no value.

OK.

A brief perusal of those discussions gives me no reason to think NULLS are necessary.

Furthermore, they reflect some sort of internal Codd/Date debate as to how to handle NULLs. Something about 2nd and 3rd order logic (my mathematics is too rusty to get anything more than an instinctive grasp of this)

What were the two positions, hypersummarised?

If everyone is clear NULLS shouldnt be used, why the debate as to what to do about them ? Received on Thu Dec 27 2007 - 03:46:26 CET