Re: Multiple-Attribute Keys and 1NF
Date: Sat, 01 Sep 2007 12:17:51 GMT
"Brian Selzer" <brian_at_selzer-software.com> wrote in message
> "David Cressey" <cressey73_at_verizon.net> wrote in message
> > "JOG" <jog_at_cs.nott.ac.uk> wrote in message
> > news:1188556656.192653.305160_at_r23g2000prd.googlegroups.com...
> >> Well I've never suggested multiple values contained in a collection.
> >> But yes as I said, multiple roles does break the guaranteed access
> >> rule. My question is now (in the continuuing hunt for the theory
> >> behind 1NF) is why on earth would that be a problem? I don't see any
> >> affect on the relational algebra.
> > I honestly think that the impetus behind "normalization" in the Codd
> > paper is more of a stopgap than a theory. (I'm not familiar with the
> > 1969
> > paper, and I only read the 1970 paper after I began participating in
> > discussions in c.d.t.) In the 1970 paper, Codd suggests that it may be
> > worthwhile to consider the subset of schemas that contain only atomic
> > attributes. (He didn't use the word "schemas", but I hope I can use it
> > without introducing confusion.)
> The whole point of 1NF boils down to the following two sentences from the
> June, 1970 article: "The adoption of a relational model of data, as
> described above, permits the defelopment of a universal data sublanguage
> based on an applied predicate calculus. A first-order predicate calculus
> suffices if the collection of relations is in normal form." Therefore,
> impetus behind "normalization" is to model the universal data sublanguage
> after a first-order logic rather than some higher order logic.
Thank you, Brian. This clarifies the issue enormously for me. Received on Sat Sep 01 2007 - 14:17:51 CEST