Re: Two relations with the same attributes

mAsterdam wrote:
> Cimode wrote:
> > mAsterdam wrote:
> >> Cimode wrote:
> >>> If 2 relations have the same attributes then they should be one
> >>> relation.
> >> No. As long as the name of the relation and the meaning of the
> >> propositions differ it is ok to have two relations with the same
> >> attributes. The meaning of the propositions depends on the external
> >> predicate.
> >
> > I see your point...
> > Thank your for pointing that out but such definition is valid only for
> > SQL systems. I should have stated that the proposed definition assumes
> > an implementation that supports domain derivability (in a word, forget
> > SQL)
>
> SQL has nothing to do with it.
>
> Is it ok to have two different relations with the same attributes?
>
> No, you say, and you build on that.
> Yes, I say, so IMO the rest of your building is irrelevant.
>
> [snip]

I concur only with mAsterdam Cimode. According to relational theory two relations may quite happily consist of the same attributes, while being totally distinct relations - and that this has nothing at all to do with SQL. Received on Mon Sep 18 2006 - 01:33:02 CEST