But 1NF has been recently redefined by Date and others. So, what precisely
is the definition of 1NF that is required for a relational database
implementation, from your perspective? --dawn
"Bob Badour" <bbadour_at_golden.net> wrote in message
news:79ednTWAxfBHLKLdRVn_iw_at_golden.net...
> If they are not 1NF, they are not relational. They may be the deformed
> step-children of the relational model, but they are not relational.
>
> "Eric Kaun" <ekaun_at_yahoo.com> wrote in message
> news:L9O%b.18045$HM4.16491_at_newssvr31.news.prodigy.com...
> Do you mean relational as in mathematics? The relational model for data is
a
> specific application of mathematical relations. Are those examples you
give
> below really relational in the sense of the relational data model? I doubt
> it. They might have something to do with mathematic relations, but that's
a
> different thing entirely.
> "Tom Hester" <$$tom_at_metadata.com> wrote in message
> news:bac94$403f841e$45033832$27879_at_msgid.meganewsservers.com...
> This is just plain false. There have been many relational models
proposed
> that are not 1NF. See for example, ABITEBOUL, S.; BIDOIT, N. Non first
> normal form relations to represent hierarchically organized data. In:
PODS,
> 1984. Proceedings. . .Note the date: 1984. This is supposed to be a
> database theory board but it seems more religious than theoretical!
>
> "Alfredo Novoa" <alfredo_at_ncs.es> wrote in message
> news:403f7915.12870647_at_news.wanadoo.es...
> > On Fri, 27 Feb 2004 08:01:43 -0600, "Dawn M. Wolthuis"
> > <dwolt_at_tincat-group.com> wrote:
> >
> > >> The Relational Model permits relation typed attributes, so
> > >> "multivalued" does not have any advantage. Collection typed
> attributes
> > >> don't violate 1NF.
> > >
> > >Yes, so the theory in RDM is evolving to the point where it might
> become
> > >more practical in its application.
> >
> > The understanding of The Relational Model is better now than in the
> > 70's, but the model is always the same.
> >
> > But relation typed values in base relations seem to have little
> > utility. The only good practical use I have found to the moment is to
> > use them to implement a candidate keys relation variable of a catalog.
> >
> > > But while each RDBMS vendor seems to
> > >have a means now of storing an array (or relation or other
> collections),
> > >querying against this data is done differently by each vendor, it
> seems,
> > >although SQL-99 has a means of doing this (and perhaps more db
vendors
> are
> > >employing that standard, but when I checked in 2002 there was no
> > >consistency).
> >
> > As you heared hundreds of times, SQL is not relational. You will not
> > find the term relational in the SQL specifications.
> >
> > >> Relations are in 1NF by definition. With a RDBMS you can not
violate
> > >> 1NF even if you want.
> > >
> > >You can violate any of the other normal forms, but not 1NF.
> >
> > Because you have no way. Relations are in 1NF by definition, otherwise
> > they are not relations. If a DBMS does not use relations then it is
> > not a RDBMS, so if you can violate 1NF then you are not using a RDBMS.
> > A simple tautology.
> >
> >
> > Regards
> > Alfredo
>
>
Received on Fri Feb 27 2004 - 15:21:56 CST
