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