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Date: Wed, 4 Nov 2009 11:37:41 -0700
Message-ID: <dcc563d10911041037p5fda84dv1c003c97c112cfc7@mail.gmail.com>
Subject: Re: DDL problems: Referential issue?
From: Scott Marlowe <scott.marlowe@gmail.com>
To: Leif Biberg Kristensen <leif@solumslekt.org>
Cc: pgsql-sql@postgresql.org
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On Wed, Nov 4, 2009 at 11:36 AM, Leif Biberg Kristensen
<leif@solumslekt.org> wrote:
> On Wednesday 4. November 2009 19.24.29 Scott Marlowe wrote:
>> You're referencing a single column, which does not have a unique key
>> on it. =A0Being part of a two column unique PK index doesn't count, as
>> you could have an entry where one column or the other repeats on its
>> own while the other column changes. =A0You might want the syntax:
>>
>> FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn
>> [, ... ] )
>>
>> where you FK a pair of columns to a pair of other columns.
>
> Thank you very much!
>
> pgslekt=3D> CREATE TABLE participant_notes (
> pgslekt(> =A0 =A0 person_fk =A0 INTEGER,
> pgslekt(> =A0 =A0 event_fk =A0 =A0INTEGER,
> pgslekt(> =A0 =A0 part_note =A0 TEXT,
> pgslekt(> =A0 =A0 FOREIGN KEY (person_fk, event_fk) REFERENCES participan=
ts
> (person_fk, event_fk)
> pgslekt(> );
> CREATE TABLE
>
> I'd missed that particular syntax.
>
> This table is now without a primary key, but is that a problem? I don't e=
xpect
> it to grow beyond maybe a few thousand rows.

Hard to say, but if you really need a PK, you can always create one later.