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

"Roy Hann" <specially_at_processed.almost.meat> wrote in message news:9LCdna8B3LW2VJjfRVn-rg_at_pipex.net...
> "Alfredo Novoa" <alfredo_novoa_at_hotmail.com> wrote in message
> news:h6da01hfpdq3f6fg384g5l0t5dd7dd1std_at_4ax.com...
> > On Fri, 4 Feb 2005 13:37:17 -0500, "Alan" <alan_at_erols.com> wrote:
> >
> > >Nothing has changed.
> >
> > It has changed, but it seems that you are not aware of that.
> >
> > > 1NF means (and has always meant) that all values are
> > >atomic (simple, indivisible)
> >
> > Atomic is not a precise word. We can not base any precise definition
> > on that term.
>
> Alan is confused, but your comment, erudite though it is, is irrelevant.
>
> 1NF does not "mean values are simple or indivisible".

Well, then Elmasri and Navathe are confused, as I quoted directly from the book (which is used in many leading universities).

 It just says that for
> the purpose of the relational theory, the divisibility (or internal
> structure) of values of a given type is of no interest or use within the
> theory. The theory does not make use nor reference to the internal
> structure of a value of any type. The theory therefore does not need to
> define what atomic means. The term "atomic" is a just a narrative
> short-hand that Codd used to say, "That's stuff I don't care about, so
> forget about it from now on as you read this paper." I can't think of any
> other theory where a precise definition is demanded for things that are
> *intended* not to be discussed. Plane geometry isn't required to define
> colour for the purpose of excluding it from discussion.
>
> There is nothing in RT that *prevents* values from being divisible, there
> never was, and it would plainly be stupid to want it that way.
>

I am not the one who is confused. You just redefined "atomic" as meaning "divisible". It Codd intended 1NF to include divisible attributes, he would have used the word "divisible", not "atomic". Received on Sun Feb 06 2005 - 16:36:38 CET