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

"Paul" <paul_at_test.com> wrote in message news:42079da8$0$34063$ed2e19e4_at_ptn-nntp-reader04.plus.net...

> Alan wrote:


>>> Roy Hann wrote:


>>>

>>>> 1NF does not "mean values are simple or indivisible".  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.

>>>

>>> This sounds to me like an excellent summary of what "1NF" and

>
> I don't see a conflict between the extract below and what Roy said above. 
> Just that the text below is a bit on the verbose and practical side, and 
> the above is a more abstract, concise and clear version.
>
> I don't think most of the people here actually disagree with the basics, 
> just that there is a problem with expressing the ideas in written language 
> such that they aren't misinterpreted.

I think it would be great to have 1NF in our currently-not-being-addressed glossary of terms (mAsterdam - any chance you could send the current version?) so that we can point to that for any future discussions. Given that XML does not require 1NF (by most definitions), this topic is not going away any time soon and starting such discussions by first getting everyone on the same page with a definition just holds up progress.

Can we find a definition that is clear; preferably concise; is not about history (i.e. is a good definition for today); and does not require any redefinition of mathematical terms for which there is considerable agreement (such as relation)? I suspect that whatever we come up with would contradict Date & Darwin, so if we could additionally ensure that the definition is mainstream and what the industry accepts as 1NF, then perhaps we need a new name for the new definitions put forth by them? Just a thought. --dawn

> Paul.
>