Re: Multiple-Attribute Keys and 1NF


"mAsterdam" <mAsterdam@xxxxxxxxxxx> wrote in message
news:46d609da$0$243$e4fe514c@xxxxxxxxxxxxxxxxx
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.


.