From: | erwan ancel <erwan(dot)ancel(at)free(dot)fr> |
---|---|
To: | Patrick Welche <prlw1(at)newn(dot)cam(dot)ac(dot)uk> |
Cc: | Jan Wieck <JanWieck(at)Yahoo(dot)com>, Bruno Wolff III <bruno(at)wolff(dot)to>, PostgreSQL-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: check constraint |
Date: | 2003-06-09 07:42:10 |
Message-ID: | 1055144529.3253.3.camel@brisedorient |
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Thread: | |
Lists: | pgsql-general |
Well, I don't think so: the problem concerns one record of A and one
record of C. This means that they would be 2 different records of the
table which both A and C inherit. The problem stays.
Le dim 08/06/2003 à 21:02, Patrick Welche a écrit :
> > >>On Mon, Jun 02, 2003 at 10:52:00 +0200,
> > >> erwan ancel <erwan(dot)ancel(at)free(dot)fr> wrote:
> > >>> Hi,
> > >>> I would like to know if it is possible to set "complex" constraints on
> > >>> databases such as:
> > >>>
> > >>> A->B means that in table A, each record references a record of table B
> > >>> (or NULL)
> > >>>
> > >>> so we have:
> > >>>
> > >>> A->B
> > >>> C->B
> > >>> D->C
> > >>> D->A
> > >>> constraint: for one record of D, D->A->B = D->C->B
>
> Could inheritance be used?
>
> D -> A -> B
> D -> C -> B
>
> suggests that A and C are similar. I have never tried using inheritance -
> could you put the constraints on a table which both A and C inherit?
>
> Cheers,
>
> Patrick
>
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