Re: Foreign superkey support
From: Jon Heggland <jon.heggland_at_idi.ntnu.no>
Date: Wed, 09 Aug 2006 15:03:47 +0200
Message-ID: <ebcmje$slu$1_at_orkan.itea.ntnu.no>
Date: Wed, 09 Aug 2006 15:03:47 +0200
Message-ID: <ebcmje$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.
--
Jon
Received on Wed Aug 09 2006 - 15:03:47 CEST