Re: DDL problems: Referential issue?

On Wednesday 4. November 2009 21.03.26 Scott Marlowe wrote:
> On Wed, Nov 4, 2009 at 11:53 AM, Leif Biberg Kristensen
> > This looks strange to me, but it works:
> >
> > pgslekt=> CREATE TABLE participant_notes (
> > pgslekt(> person_fk INTEGER NOT NULL,
> > pgslekt(> event_fk INTEGER NOT NULL,
> > pgslekt(> part_note TEXT,
> > pgslekt(> PRIMARY KEY (person_fk, event_fk),
> > pgslekt(> FOREIGN KEY (person_fk, event_fk) REFERENCES participants
> > (person_fk, event_fk)
> > pgslekt(> );
> > NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index
> > "participant_notes_pkey" for table "participant_notes"
> > CREATE TABLE
>
> Note that this will limit you to one record in your participant notes
> for each record in the participants table.

That's exactly what I want :)

For all practical purposes, the design is equivalent to adding a TEXT column
to the participants table. But as I expect a very small number of notes
compared to the number of rows in the participants table, I prefer to create a
small extra table rather than having a large number of null values in the
participants table. Performance-wise, it probably doesn't matter much. It's
more a matter of taste.

--
Leif Biberg Kristensen
http://solumslekt.org