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Home -> Community -> Usenet -> comp.databases.theory -> Re: Key attributes with list values was Re: What are the differences ...KEY

Re: Key attributes with list values was Re: What are the differences ...KEY

From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 25 Feb 2006 20:57:59 -0800
Message-ID: <1140929879.099538.321390@z34g2000cwc.googlegroups.com>


dawn wrote:
>
> Correct (if I understand). What does it mean that a list is a key? If
> I change one value in the list, does that make it a new key? I would
> think so.

If we substitute "int" for "list", what does the above look like?

"What does it mean that an int is a key? If I change one bit in the int, does
that make it a new key? I would think so."

I agree with both the list and the int version of the sentence. After all,
why should the particular type of the key change the way key values behave?

> It might [make sense to] model a proposition something like
>
> The team with people whose ID's are 112233 and 123456 has a best run of
> 38 seconds in the potato sack race.

Sure, that seems like a fine proposition to me.

> Most data modelers would choose to provide a team identifier rather
> than implement a multivalued ID (even MV developers).

As would I.

But again, in my view it's not generally a language designer's job to try
to dictate best practice. I instead like the idea of orthogonal features,
and recursive definitions. I like to make as many things as possible have
first class status in the language. (Although I draw the line at first class
variables a la SML, since that introduces identity.) If I decide that lists
shouldn't be keys, I'm going to have to put special purpose code in just
to check for that, or else build a more complicated, more rigid model that simply can't express the idea. Neither appeals to me.

Marshall Received on Sat Feb 25 2006 - 22:57:59 CST

Original text of this message

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