Re: What to call this operator?

From: Marshall Spight <>
Date: 1 Jul 2005 08:09:24 -0700
Message-ID: <>

Jon Heggland wrote:
> In article <>,
> says...
> > With join, all keys are preserved.
> Umm... they are? What do you mean by "preserved"? Perhaps I
> misunderstand you, but a key of one of the operands is not necessarily a
> key of the result.

Okay. What rule would you propose?

In fact, since I proposed that rule in the above-referenced message, I did think of a counterexample which would make some relations unjoinable, which isn't good.)

Marshall Received on Fri Jul 01 2005 - 17:09:24 CEST

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