Re: check constraint

well, no... these are not direct foreign keys. The constraint here is
that for a given record of D, B pointed by A pointed by the given D must
be the same as B pointed by C pointed by the given D.

This is not a foreign key, or foreign keys are much more than what I
thought.
        Erwan

Le lun 02/06/2003 à 15:08, Bruno Wolff III a écrit :
> On Mon, Jun 02, 2003 at 10:52:00 +0200,
>   erwan ancel <erwan.ancel@free.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
> >
> >     Hope it is clear enough.
>
> It looks like you are talking about foreign keys. Postgres has foreign key
> constraints. You can look at the create table documentation to see how
> to define them when creating a table.
>
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