Re: more on delete from join

"Marshall" <marshall.spight_at_gmail.com> wrote in message news:3f70f7cf-4770-4a66-a978-33ca1dd6ced0_at_u20g2000prg.googlegroups.com... On Aug 30, 11:52 pm, "Mr. Scott" <do_not_re..._at_noone.com> wrote:

<snip>

<quote>
> > Some systems of equations are overspecified, some are underspecified,
> > and some are uniquely specified. Which one of those do you think
> > might be a good candidate for the kind of view update that
> > would succeed? Would fail?
>
> I don't think systems of equations apply to view updates, because view
> updates involve more than one state of affairs, the state before the
> update
> and the state after. Systems of equations are either independent of state
> or involve one and only one state, so I don't think they are even relevant
> to the problem of view updates.

To me, the question is, do my ad hoc view update rules give better results, or does my equation solving approach work better? My expectation is that the latter is true, but as I said, I haven't worked out all the detail yet. </quote>

While I am still uncomfortable with the idea of the premises of an argument following from its conclusion, if your equation solving approach would permit a larger class of views to be considered 'updatable,' then it would definitely be worth pursuing. Received on Tue Sep 01 2009 - 06:33:07 CEST