Re: Foreign superkey support

"David Cressey" <dcressey_at_verizon.net> wrote in message news:X9ECg.1556$QK.1095_at_trndny06...
>
> "Jon Heggland" <jon.heggland_at_idi.ntnu.no> wrote in message
> news:ebcmje$slu$1_at_orkan.itea.ntnu.no...
> > David Cressey wrote:
> > > The above surprises me. I had thought that the CHECK constraint in
> Rdb/VMS
> > > was sufficiently general to express any and all Boolean conditions,
and
> > > that the CHECK constraint would have been covered by numerous
> competitors.
> > > Am I wrong about the span of the CHECK constraint? Or do most DBMS's
> lack
> > > support for the CHECK constraint?
> >
> > What precisely do you mean by a CHECK constraint? The "CHECK" keyword is
> > used for several different kinds of constraints in SQL, with varying
> > degrees of support/implementation.
> > --
>
> I was unaware of the differences you describe.
>
> The closest I can come to being specific is the CHECK constraint as
> implemented in Rdb.

Sorry, make that DEC Rdb/VMS sold to Oracle Corp. in 1994, and known as Oracle/Rdb. Received on Thu Aug 10 2006 - 13:11:59 CEST