Re: a union is always a join!
Date: Sun, 22 Mar 2009 12:26:25 GMT
Message-ID: <R7qxl.1720$SU3.1350_at_nwrddc02.gnilink.net>
"Brian Selzer" <brian_at_selzer-software.com> wrote in message
news:50qxl.22730$Ws1.10290_at_nlpi064.nbdc.sbc.com...
> 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