Re: Multiple-Attribute Keys and 1NF

"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message news:46d609da$0$243$e4fe514c_at_news.xs4all.nl...
> David Cressey schreef:
> > It took me a while to realize that what you meant from your original
> > description was that
> > "a green and yellow wire means earth". I had thought you meant "a green
> > wire means earth" and "a yellow wire means earth". Pardon me for being
> > dense.
>
> Dense? Electrocuted!
>
> > Clearly what we have here is not a domain of colors, but a domain of
color
> > codes, where a color code contains one or more colors, and maybe a
"thick
> > or thin" qualifier on each color.
>
> No. Please do not dive into the subleties just because they are there.
> It is code - nothing else. That the symbols are colors, not characters
> as we are more used to, does not change the essence of the example.
>
> > It's not clear to me why you need to able to query on simple colors,
unless
> > you need to decompose the color coding scheme into its constituent parts
for
> > some reason.
>
> Because it is code, the colors as such are irrelevant.

Agreed. But the entire gist of JOG's post seems to me to be the situation where the constituent parts of a code are, for some reason, themselves part of the sybject under discussion.

>
> > There are lot of code domains where each code is made up of a set of
more
> > primitive elements.
> > Perhaps a very relevant one might be "character code". If I have the
> > following primitive elements:
> >
> > B1, B2, B4, B8, B16, B32, B64, B128
> > (which might be an odd way of labelling bits 0 through 7 of a byte), I
can
> > think of the character code for 'A' as being B64+B1. Now I could query
on
> > all the character codes without necessarily having an operator that
would
> > yield "all the codes that include B1".
> >
> > I think that the colors, as constituents of color codes, play the same
role
> > as bits, as constituents of character codes. Do you agree?
>
> I do, but does Jim?

Yes, that's the question. Received on Thu Aug 30 2007 - 06:33:35 CEST