Re: table inheritance and foreign key troubles

On Tuesday, 11. September 2001 10:04, Kevin Way wrote:
> I'm having a little trouble with some inherited tables and a foreign
> key. Here's a simplified case, to show the trouble.
>
> CREATE TABLE node (
> node_id SERIAL NOT NULL,
> name TEXT NOT NULL,
> PRIMARY KEY (node_id)
> );
> -- works just fine
>
> CREATE TABLE users (
> email TEXT NOT NULL
> ) INHERITS (node);
> -- so far so good....
>
> CREATE TABLE item (
> reason TEXT NOT NULL,
> author_id INT NOT NULL REFERENCES users (node_id)
> ) INHERITS (node);
> ERROR: UNIQUE constraint matching given keys for referenced table
> "users" not found

That means, there is no UNIQUE constraing on users.node_id ;-)
Since users inherits that field from node, just make node.node_id
unique, or even a primary key.

> Does this operation just require differing syntax, because the
> referenced field is inherited from another table, or is this not
> possible?

In previous versions of Postgres it was possible to reference non-unique
fields. With 7.1.x this is, correctly, no longer possible. Inheritance
doesn't have anything do to with it in your case, though.

Hope that helps,

Christof
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