Re: Multiple-Attribute Keys and 1NF
Date: Tue, 28 Aug 2007 22:27:58 +0200
> I am still fighting with the theoretical underpinning for 1NF.
My answer won't help you in that quest, sorry. I like the example, but I don't think it illustrates a NF problem. Yet I like it because I think it illustrates a much more basic, non-formal issue.
> As such, any comments would be greatfully accepted.
> The reason for my concern is that there
> /seems/ instances where 1NF is insufficient. An
> example occurred to me while I was wiring up a dimmer switch (at the
> behest of mrs. JOG, to whom there may only be obeyance). Now I don't
> know the situation in the US, but in the UK a while back the colour
> codes for domestic main circuit wiring changed. Naturally the two
> schemes exist in tandem, as exhibited in every house I've had the joy
> of doing some DIY in:
> Brown -> live.
> Red -> live
> Blue -> neutral.
> Black -> neutral.
> Green and yellow -> earth.
This is dictionary of a little language. left of the '->' is the code, to the right of it is the explanation. The code is expressed with colors as symbols, just as in our phonographic latin the words are expressed with soundsymbols. A color-alphabet. The codes are not colors as such. Your information need is the code explanation, not anything about the colors.
> The issue with encoding these propositions is that the candidate key
> for each proposition may consist of one _or_ two colours.
This is similar to asking how many characters can make up a word or how many words a sentence.
> Now I have a
> couple of options, none of which seem satisfactory. I could leave
> green & yellow as some sort of set-value composite, but obviously this
> would affect my querying capabilities, so thats out straight off the
> bat. Similarly adding attributes Colour1 and a nullable Colour2 is
> simply so hideous it isn't worth consideration. So, I could ungroup to
> give me:
> Colour Type
> Brown live
> Red live
> Black neutral
> Blue neutral
> Green earth
> Yellow earth
These problems arise because you have taken it upon you to model language itself instead of a mere administrative problem. This is a non-trivial task :-)
[snip more language modeling attempts]
> I am having a crisis of faith with the way 1NF is currently viewed.
> Any ideas to solve my dilemma? Am I on my own in being perturbed?
Received on Tue Aug 28 2007 - 22:27:58 CEST