Re: Codd's Information Principle
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sun, 01 Nov 2009 18:26:15 -0400
Message-ID: <4aee0b09$0$5320$9a566e8b_at_news.aliant.net>
>
> ...
>
>
> If you mean the last sentence, I could expand it by saying that for any
> given purpose, in other words any given application, I think that single
> extension must have one interpretation. Since the expression might not
> involve any algebraic operations, I think it is best to discard those in
> the interpretation, no matter how the extension was formed. I say
> 'best' because that seems sufficient to me and I don't see how including
> those ops is necessary. I would like to know what problems this causes,
> eg., I don't see that inconsistences/contradictions or loss of utility
> or inability to optimize result from it.
Date: Sun, 01 Nov 2009 18:26:15 -0400
Message-ID: <4aee0b09$0$5320$9a566e8b_at_news.aliant.net>
paul c wrote:
>> paul c wrote:
>
> ...
>
>>> Didn't mean to suggest otherwise. Sometimes the immediate expert >>> objection to the 'primrose path' turns out to be an advantage if the >>> idea is allowed to breath. >>> >>> But one point seems very immediate to me - for any given relational >>> expression, there is only one equivalent extension. >> >> I don't follow that at all.
>
> If you mean the last sentence, I could expand it by saying that for any
> given purpose, in other words any given application, I think that single
> extension must have one interpretation. Since the expression might not
> involve any algebraic operations, I think it is best to discard those in
> the interpretation, no matter how the extension was formed. I say
> 'best' because that seems sufficient to me and I don't see how including
> those ops is necessary. I would like to know what problems this causes,
> eg., I don't see that inconsistences/contradictions or loss of utility
> or inability to optimize result from it.
I cannot make sense of what you wrote. Received on Sun Nov 01 2009 - 23:26:15 CET