Re: Little question for RDM theoristes
Date: 16 Jun 2006 07:34:20 -0700
Looking at the rest of the thread, it confirms my opinion that the question was biased and create more confusion because it assumes the false premise that relation = relvalues...There is no point discussing such question...
> 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 - 16:34:20 CEST