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Re: What predicates the following relation represents

From: Paul <paul_at_test.com>
Date: Thu, 01 Apr 2004 14:20:43 +0100
Message-ID: <QEUac.26710$h44.3527695@stones.force9.net>


Mikito Harakiri wrote:
> SALES
> =====
> PART SOLD
> ---- ---
> nuts 10
> nuts 15
>
> Is SALES a legal relation? Is database really a repository of facts?

It depends on the meaning given to the relation.

Suppose the predicate was:
"At some point in time, we have sold a batch of PART of size SOLD."

So the relation would be used for asking questions such as:

"Have we ever sold a batch of 7 nuts?"
"Show me all the parts we have ever sold as a batch of 10"
"Which is the most popular batch size for purchasers of nuts"

And your candidate key would be both columns.

Paul. Received on Thu Apr 01 2004 - 07:20:43 CST

Original text of this message

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