Re: [GENERAL] foreign key to multiple tables depending on another column's value

Em 29-05-2013 12:51, Vick Khera escreveu:
>
> On Wed, May 29, 2013 at 9:58 AM, Rodrigo Rosenfeld Rosas
> <rr(dot)rosas(at)gmail(dot)com <mailto:rr(dot)rosas(at)gmail(dot)com>> wrote:
>
> I know I could use a trigger, or some check constraint maybe, to
> ensure the field exists upon insert (or update), but I can't
> ensure the database will become inconsistent in case I remove a
> mapped field from the other schema.
>
> Now I can finally explain my question: is it possible that I set
> some sort of foreign key whose referenced table and column would
> depend on the value of another column?
>
>
> The FK tests are basically triggers, but highly optimized.
>
> That said, the way they enforce the integrity is by having a trigger
> on both tables. So for your custom need here, you would want to put a
> trigger on the referenced table to disallow deleting a value that is
> still referenced, or do whatever appropriate action upon delete/update
> your application needs.
>

Ok, thanks. I just wanted to be sure there wasn't some hidden feature of
PostgreSQL I wasn't aware of yet...

You know, I'm always learning something new on PG, so it worths trying
to ask first ;)

Cheers,
Rodrigo.