Re: c.d.theory glossary - NULL

"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message news:408fc2a1.16584517_at_news.wanadoo.es...
> On Wed, 28 Apr 2004 08:45:38 -0400, "Laconic2" <laconic2_at_comcast.net>
> wrote:
>
> >
> >"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message
> >news:408ec600.632719_at_news.wanadoo.es...
> >> The zero byte is at the physical level and the null at the logical
> >> level.
> >...
> >> The bit vector is at the physical level and the SQL nulls at the
> >> logical level.
> >
> >In this case, it's a distinction without a difference.
>
> There is a fundamental difference, the bit vector is hidden to the
> users and it could be changed by any other physical representation
> without affecting the logical model. That's data independence.
>
> Bit vectors are bit vectors, not nulls
>
>
> Regards
>
Received on Wed Apr 28 2004 - 18:00:20 CEST