Re: Towards a definition of atomic
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Fri, 01 Feb 2008 15:02:03 -0400
Message-ID: <47a36cad$0$4068$9a566e8b_at_news.aliant.net>
>
> If one goes just a bit further, one might say the only such operator
> is equality, which is clearly necessary for natural join, etc. A theta
> join, for example, is a join of two operand relations and a further
> join with the < relation.
Date: Fri, 01 Feb 2008 15:02:03 -0400
Message-ID: <47a36cad$0$4068$9a566e8b_at_news.aliant.net>
Marshall wrote:
> On Feb 1, 8:15 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:
>
>>The important thing in this discussion is: The relational model treats >>domain values as neither composable nor decomposable. They are >>simply values upon which one may evaluate defined operations.
>
> If one goes just a bit further, one might say the only such operator
> is equality, which is clearly necessary for natural join, etc. A theta
> join, for example, is a join of two operand relations and a further
> join with the < relation.
Yes, the RM only requires one operation, and one can phrase all other simple operations as relations of some degree. What about aggregates? Received on Fri Feb 01 2008 - 20:02:03 CET