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Re: Little question for RDM theoristes

From: Cimode <cimode_at_hotmail.com>
Date: 16 Jun 2006 06:45:12 -0700
Message-ID: <1150465512.937028.262320@u72g2000cwu.googlegroups.com>

Erwin a écrit :

> > Your question implies relations = relvalues...which if I follow this
> > false premise reasonning would lead to relations that have similar
> > relvalues being equal which is totally false...2 relvar with same
> > relvalues are NOT necessarily equal.
>
> TTM Chapter 4, RM prescription 10 :
>
> "A relation value (relation for short) ..."
>
> Therefore at least to Chris Date, 'relations=relvalues' is most
> certainly true. I'd say that's a strong indication of just how much
> "false premise" there is within.
>
> > This question is totally irrelevant if you consider a relation as being
> > equal to a relvalue...

Considering you confuse relvalues and relations and seem to persist...I am doubtful the rest of the comments will be any useful but I will take time to respond one last time....

> This question is not irrelevant at all since the heading is regarded as
> the definition of the applicable relation type. And for values to be
> equal, they must most certainly be of the exact same type, inheritance
> issues notwithstanding of course

What do you mean *regarded* as a definition type...Can't you think about the consequences of doing that?

If you consider header metadata as a part of relation type deifnition, you include human interpretation in the definition of the relation....RM only bridges the gap between formal representation of relations and human interpretation...human interpretation should be done as a last step not as primary step...Totally contradicts the purpose of RM.

header has been included in formal definitions only to help poor SQL people make some sense out of RM because they can not do without header to make sense out of a relvar... Received on Fri Jun 16 2006 - 08:45:12 CDT

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