Re: is pivoted phones view updateable?
Date: 11 Nov 2006 11:43:52 -0800
Message-ID: <1163274232.222768.120900_at_k70g2000cwa.googlegroups.com>
NENASHI, Tegiri a écrit :
> Cimode wrote:
> > Aloha Kakuikanu a écrit :
> >
> > > Tchuzhie Giri wrote:
> > > > It is not "OK" so long as one does not have your rules of updatability.
> > > > You put a pile of symbols on the pile of symbols: it does not have
> > > > sense without the rules. Please provide the rules, simple examples
> > > > and then one can go to more complex examples.
> > >
> > > Given two relation variables
> > >
> > > Y(n, #) -- aka WorkPhones(name, number)
> > > and
> > > Z(n, #) -- aka CellPhones(name, number)
> > >
> > > and two relation constants
> > >
> > > A = {(t='work')}
> > >
> > > and
> > >
> > > B = {(t='cell')}
> > >
> > > is the view
> > >
> > > X = (Y /\ A) \/ (Z /\ B) -- aka ConsolidatedPhones
> > >
> > > updateable? There is no minus operator involved. The only two RA
> > > operators are join /\ and union \/.
> >
> > How exactly do you intersect Y and A AND Z and B with no FK? What unary
> > relation is t?
>
> It is the private notation of the person that posted:
>
> /\ -- join
> \/ -- union
>
> Y join A is Cartesian product, also Z join B:
>
> Let Y be {('y1', 1), ('y2', 2)} then Y join A = {('y1', 1, 'work'),
> ('y2', 2, 'work)} et cetera.
>
> The question is to arbitrate the insertion of the union with 'work' and
> 'cell'. C.J. Date has offered the thought and also critiqued it.
>
> --
> Tegi
Thanks for clarifying. I do not see the purpose or the usefulness of
the question. Maybe Aloha could state what he wants to get at?
Received on Sat Nov 11 2006 - 20:43:52 CET