Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Is it Possible to Enforce This Relationship at the DB Level?

Re: Is it Possible to Enforce This Relationship at the DB Level?

From: dutone <dutone_at_hotmail.com>
Date: Fri, 19 Oct 2007 16:44:13 -0000
Message-ID: <1192812253.242886.40630@q3g2000prf.googlegroups.com>


On Oct 16, 4:03 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.

What I was trying to say is that not all constraints can be enforced via relationships, hence the need for a RDMS to allow one to create a high level constraint with statements like check assertion.

My original question appears to fall into this category, since I cannot see away to guarantee that the Cell Config table will include only rows of the Field table that are children of the Spec table referenced by Spreadsheet Config.

Although maybe something was wrong with my model, which is why I initially posted my question.

Thanks Received on Fri Oct 19 2007 - 11:44:13 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US