Re: Two relations with the same attributes
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Mon, 18 Sep 2006 01:08:21 +0200
Message-ID: <450dd4f2$0$4524$e4fe514c_at_news.xs4all.nl>
>
> 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.
Date: Mon, 18 Sep 2006 01:08:21 +0200
Message-ID: <450dd4f2$0$4524$e4fe514c_at_news.xs4all.nl>
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] Received on Mon Sep 18 2006 - 01:08:21 CEST