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From: Johannes Lochmann <johannes.lochmann@chello.at>
To: "Matthew Nuzum" <cobalt@bearfruit.org>,
	<pgsql-sql@postgresql.org>
Subject: Re: constrains questios ..
Date: Tue, 11 Feb 2003 19:04:14 +0100
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On Tuesday 11 February 2003 18:41, Matthew Nuzum wrote:
> Can you please demonstrate the syntax you would use to create the
> constraints?  I'm not real clear on this and my attempts haven't
> produced what I wanted.

Checked the docs? They are really good at this point. Anyways.

The following creates Tables A, B and AB. A and B have an id and a text fie=
ld,=20
AB connects them (N:M relation).

create table A (
	id integer not null primary key,
	something varchar(16)
);

create table B (
	id integer not null primary key,
	otherthing varchar(16)
);

create table AB (
	id_a integer not null,
	id_b integer not null,

	constraint pk_AB primary key(id_a, id_b)
);

create unique index u_A_something on A (something);
create unique index u_A_otherthing on B (otherthing);

alter table AB add constraint fk_AB_A_exists foreign key(id_a) references=
=20
A(id);
alter table AB add constraint fk_AB_B_exists foreign key(id_b) references=
=20
B(id);

HTH

Johannes Lochmann

--=20
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