Re: Can we solve this -- NFNF and non-1NF at Loggerheads

"Tom Ivar Helbekkmo" <tih+nr_at_eunetnorge.no> wrote in message news:86mzuhd51g.fsf_at_athene.hamartun.priv.no...
> "Alan" <not.me_at_rcn.com> writes:
>
> > You just redefined "atomic" as meaning "divisible". It Codd intended
> > 1NF to include divisible attributes, he would have used the word
> > "divisible", not "atomic".
>
> No, when he said "atomic", he meant something else: he meant that the
> objects in question were atomic _with respect to the theory_. That
> is, his relational theory was not concerned with what those objects
> actually were; as far as the theory went, they were atomic. This does
> not mean that they have to be scalar values; they can be _anything_.
> However, if the value of an attribute is, say, a relation, there is
> nothing in Codd's theory that looks into that relation, and lets its
> contents affect operations on the outer, "real", relations.

I refer you to the Elmasri/Navathe text, which states quite the opposite. Paraphrasing it (as I don't have it with me at the moment), 1NF means that all values are atomic (simple and indivisible - are terms used to explain "atomic" in the text), and any value must be a single value from the domain of that attribute. It does not allow nested data. It does not allow multi-valued or composite attributes. These constraints on 1NF are specifically stated in the text. Dawn has a copy. Perhaps she can look it up (look up First Normal Form).

Note that Date and Codd often disagreed. Date attempts to expland upon the theory, but it is not an expansion so much as a modification so extreme as to become something else. Date is correct that a theory is needed to explain MVAs, but foisting it upon 1NF just to have a "unified theory of normalization" (sorry Albert) is silly. Make a new theory. There's no law against it. Just don't pretend it is still 1NF. Call it MVA Normal Form. Call it Date Normal Form. Call it Dawn's Normal Form. Just don't call it First Normal Form. It isn't. It is similar to 1NF, but values don't need to be atomic. That should satisfy the pre-relational programmers among you who are at the core of this nonsense. Next thing I'm going to hear is that linked lists are really 2NF, and adding additional pointers to other lists allows for 3NF and foreign key constraints. Received on Sun Feb 06 2005 - 20:33:15 CET