Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation
Date: Thu, 03 May 2007 06:58:28 GMT
Message-ID: <oKf_h.7076$rO7.4656_at_newssvr25.news.prodigy.net>
"Jon Heggland" <jon.heggland_at_idi.ntnu.no> wrote in message
news:f1c09b$8bk$1_at_orkan.itea.ntnu.no...
> Brian Selzer wrote:
>> Clarification. In a closed world, the assignment itself provides a frame
>> of
>> reference for comparison, so it *can* be determined whether or not the
>> values are identical, or whether or not one or more corresponding
>> relations
>> within each value are identical. As often is the case, I'm wrong: logical
>> identity can be used. On the other hand, it can only be determined that
>> a
>> tuple in a relation in one value is identical to a tuple in a relation in
>> the other. If a relation in the replaced value is neither a superset nor
>> a
>> subset of the relation with the same name in the assigned value, and if
>> more
>> than one element is different, then a mapping is required for comparison.
>> And again, since key updates have been part of the model since its
>> inception, and since surrogates aren't, assignment would permit certain
>> constraints to be bypassed--a clear violation of one of Codd's rules.
>
> Straw man. If transition constraints were tuple-based, and assignment
> would allow you to bypass them, then they would be bypassed. But I don't
> think anyone is advocating that.
> --
> Jon
Received on Thu May 03 2007 - 08:58:28 CEST