Re: DDL problems: Referential issue?

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.  Being 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.  You 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=> CREATE TABLE participant_notes (
> pgslekt(>     person_fk   INTEGER,
> pgslekt(>     event_fk    INTEGER,
> pgslekt(>     part_note   TEXT,
> pgslekt(>     FOREIGN KEY (person_fk, event_fk) REFERENCES participants
> (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 expect
> 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.