Re: Does entity integrity imply entity identity?

From: paul c <toledobythesea_at_oohay.ac>
Date: Sun, 09 Aug 2009 01:27:36 GMT
Message-ID: <cCpfm.40191$PH1.35653_at_edtnps82>


Mr. Scott wrote:
> ,,,...
> I probably should have included D and E columns that don't allow nulls.
>
> (X,D,E) "X is an order placed on date D by customer E."
> (X,A) "A is the e-mail address for order X."
> (X,B) "B is the snail-mail address for order X."
> (X,C) "C is the delivery phone number for order X."
>
> Then there would be no question as to whether an order table would be needed
> in addition to the order_e-mail table and the order_snail-mail table.
>

Okay, that's clearer. Now I get the impression that SQL doesn't support all the FK constraints desired, Is that so? If so, does that mean that SQL can't test relations for equality? Received on Sun Aug 09 2009 - 03:27:36 CEST

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