Re: a union is always a join!

From: Walter Mitty <>
Date: Sun, 22 Mar 2009 12:26:25 GMT
Message-ID: <R7qxl.1720$>

"Brian Selzer" <> wrote in message news:50qxl.22730$

> least not algebraic differences. Once one admits that there are things in
> the universe of discourse that can appear different at different times,
> the semantics of insert, update and delete become clear: insert describes
> the beginning of the path that something travels through time, updates
> describe milestones along the path that mark changes in appearance, and
> delete describes the end of the path. So a transition consisting of a
> delete and an insert that has no apparent effect on the database makes
> perfect sense because it describes the end of one thing and the beginning
> of another.

This is mysticism. Received on Sun Mar 22 2009 - 13:26:25 CET

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