Re: abnormal forms

From: x <>
Date: Mon, 17 Apr 2006 13:32:13 +0300
Message-ID: <e1vqq4$pg9$>

"paul c" <> wrote in message news:o980g.25403$WI1.2059_at_pd7tw2no...
> x wrote:
> > "paul c" <> wrote in message
> > news:QHa%f.6021$WI1.5342_at_pd7tw2no...
> >
> > ...
> >
> >>For example, (using ttm-style braces and for convenience omitting type
> >>names), is a SUPP{S#} relation logically the same value as a SUPP{{S#}}
> >>relation that is (somehow) constrained to have only one tuple? (not to
> >>be confused with one that somehow allows multiple tuples).
> >
> >
> > Maybe you should define an abnormal join first. :-)
> >
> >
> Not sure if you were kidding, but as opposed to defining abnormal join,
> I wonder if it isn't already defined. Regardless, one would have to
> decide how join could be involved since it must be involved. Just what
> that would mean is another question. if an sva and an rva in two
> otherwise different relations have the same name would the join (or
> <AND>) of the two contain an rva or an sva or both?

I think it is a matter of definition.
If you define that "SUPP{S#} relation is logically the same value as a SUPP{{S#}}" you must investigate the operators to see what this definition would imply (if your system is consistent). The other way around, if you have the operators defined (the abnormal join for example), you could easily verify if the "SUPP{S#} relation is logically the same value as a SUPP{{S#}}". Received on Mon Apr 17 2006 - 12:32:13 CEST

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