Re: Stupid Database Tricks

From: David BL <davidbl_at_iinet.net.au>
Date: Mon, 11 Jun 2007 01:29:59 -0700
Message-ID: <1181550599.928449.313430@d30g2000prg.googlegroups.com>

On Jun 10, 4:21 am, Marshall <marshall.spi..._at_gmail.com> wrote:

> If we have proposition
> A and proposition B, and these two propositions have the same
> set of attributes, and for each attribute, the value of the attribute
> in A equals the value of the attribute in B, then A = B.

You need to word that a little more carefully

Consider predicates

P(x,y) = x < y
Q(x,y) = x > y

Then P(1,2) and Q(1,2) are different propositions even though they have the same values for all the attributes. Received on Mon Jun 11 2007 - 03:29:59 CDT