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From: Richard Huxton <dev@archonet.com>
Organization: Archonet Ltd
To: "Filipe Bonjour" <fbonjour@urbanet.ch>, pgsql-sql@postgresql.org
Subject: Re: Can arrays reference primary keys in CREATE TABLE?
Date: Wed, 14 May 2003 16:31:48 +0100
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On Friday 09 May 2003 10:21 pm, Filipe Bonjour wrote:
> Hi,
>
> I'm a rather new SQL user, and I found interesting that you can
> use "references" to make sure that a value inserted in a table is a
> primary key from another table. Something like:

Yep - referential integrity is vital.

> However, I'd like to define a table containing an array, and that
> all elements of the array be a primary key from another table, so I
> tried:
>
> create table tb (
>   a_ref     integer[] references ta(a_id)
>   );
>
> But that doesn't work, I think because an array of integers can't
> be directly compared to an integer.

Don't use arrays, use another table, e.g.

CREATE TABLE tb_items (
  tb_ref  integer REFERENCE tb,
  ta_ref integer REFERENCES ta,
  PRIMARY KEY (tb_ref,ta_ref)
);

--=20
  Richard Huxton