From: | Patrick Welche <prlw1(at)newn(dot)cam(dot)ac(dot)uk> |
---|---|
To: | Jan Wieck <JanWieck(at)Yahoo(dot)com> |
Cc: | erwan ancel <erwan(dot)ancel(at)free(dot)fr>, Bruno Wolff III <bruno(at)wolff(dot)to>, PostgreSQL-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: check constraint |
Date: | 2003-06-08 19:02:18 |
Message-ID: | 20030608200218.A18618@quartz.newn.cam.ac.uk |
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Thread: | |
Lists: | pgsql-general |
> >>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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