From: | Branden Visser <mrvisser(at)gmail(dot)com> |
---|---|
To: | Mark Lybarger <mlybarger(at)gmail(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: foreign key with where clause |
Date: | 2016-08-18 17:19:04 |
Message-ID: | CAOo4Obrt=ZnpoF41Kq8BueL+HtZ5oQGhhzApLP2oaTBmbNsa-g@mail.gmail.com |
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Thread: | |
Lists: | pgsql-general |
My first instinct would be to look into triggers. In addition to an FK
a(b_id) -> b(id), you could have an insert and update trigger on
a(b_id) and b(active) to ensure the additional constraints.
On Thu, Aug 18, 2016 at 1:10 PM, Mark Lybarger <mlybarger(at)gmail(dot)com> wrote:
> I have two tables that i want to link with a FK where the child table record
> is "active".
>
> some googling shows that i could use a function and a check constraint on
> the function, but that only works for inserts, not updates on table b.
>
> create table a (int id, text name);
> create table b (int id, boolean active);
>
> alter table a add column b_id integer;
> -- how to do this?
> alter table a add foreign key (b_id) references b(id) where b.active == true
>
> help :).
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