Re: CHECK constraint

Date sent:          Thu, 13 Mar 2003 14:35:40 +0000
From:               Ben Clewett <B.Clewett@roadrunner.uk.com>
Copies to:          pgsql-novice@postgresql.org
Subject:            [NOVICE] CHECK constraint

Ben,
Would foreign keys not be the simplest solution?

CREATE TABLE foo(

id int4 NOT NULL,
FOREIGN KEY (id) REFERENCES bar(id) ON DELETE CASCADE ON UPDATE CASCADE NOT DEFERRABLE INITIALLY IMMEDIATE,

)
In SQL standards, I belive a SELECT query is valid in a check constraint:

CREATE TABLE foo (
    a INT CHECK ( a IN ( SELECT b FROM bar WHERE .... ) )
}


> However, this seems not to be the case (yet) in PostgreSQL.
>
> Should I do this with Triggers instead?  Are there any other elegent
> methods of doing the same?


Ben


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