PostgreSQL 7.2 Documentation

3.3. Foreign Keys

[..]
CREATE TABLE cities (
name varchar(80) primary key,
location point
);

CREATE TABLE weather (
city varchar(80) references weather,
temp_lo int,
temp_hi int,
prcp real,
date date
);

Table weather refernces table cities and not itself.
Best regards

Mathias Zajaczkowski,
UBIK S.A.
Av. Cortot 7d,
1260, Nyon, Switzerland
Tel : +41 22 362 04 60
Fax: +41 22 362 04 61
mailto:mathias(at)ubik(dot)ch
http://www.ubik.ch