Re: Is it Possible to Enforce This Relationship at the DB Level?
Date: Mon, 22 Oct 2007 11:39:04 -0700
On 19 oct, 20:34, dutone <dut..._at_hotmail.com> wrote:
> On Oct 18, 8:57 pm, Ed Prochak <edproc..._at_gmail.com> wrote:
> > On Oct 16, 7:03 am, David Portas
> > <REMOVE_BEFORE_REPLYING_dpor..._at_acm.org> wrote:
> > > On 15 Oct, 22:59, dutone <dut..._at_hotmail.com> wrote:
> > > > I'd like to enforce this based on the data model and its
> > > > relationships.
> > > > Although to me, it doesn't seem possible without an additional layer
> > > > of logic.
> > > > The need for a check assertion in a RDMS tells me that cerain
> > > > cituations must be enforced at a higher level. This is one of them I
> > > > guess.
> > > Maybe your definition of a data model differs from mine. All such
> > > constraints are surely part of that model irrespective of what syntax
> > > the DBMS uses.
> > > If you have some particular DBMS in mind then maybe someone will have
> > > other suggestions about features supported by that product. Perhaps a
> > > redesign would also be possible but I'm reluctant to begin a design-by-
> > > newsgroup exercise.
> > > --
> > > David Portas
> > I'm not trying to start a group design effort, but his original model
> > certainly seems to me to have the Cell Config in the wrong place. At
> > the logical lege, the connections should be described verbally (the
> > cardinality can be there but blank connections between entities leaves
> > too many unidentified assumptions.
> Wrong place, how so? The diagram got screwed up so let me clarify.
> The CLIENT can provides a SERVICE
> Each SERVICE is described by a SPREADSHEET
> The SPREADSHEET must conform to a SPEC
> A SPEC mandates that one supply values for its FIELDS
> A SPREADSHEET has many CELLS which correspond to to FIELDS of its
> chose SPEC
So these are your conceptual rules...What an ignorant. You don't even know what a relation is. Received on Mon Oct 22 2007 - 20:39:04 CEST