Sandro Dentella <sandro@xxxxxxxx> writes: > this works in fact, and it's simpler. But I don't really understard why I > should put it in this way. The other way seems to work for me: regression=# create table film_film (id int, titolo text); CREATE TABLE regression=# create table vota_punteggio(film_id int, user_id int, voto int); CREATE TABLE regression=# insert into film_film values(1, 'one'); INSERT 0 1 regression=# insert into film_film values(2, 'two'); INSERT 0 1 regression=# insert into vota_punteggio values(1, 2, 10); INSERT 0 1 regression=# SELECT f.id, f.titolo, p.voto regression-# FROM film_film f LEFT OUTER JOIN vota_punteggio p regression-# ON (f.id = p.film_id) regression-# WHERE (p.user_id = 2 OR p.user_id IS NULL); id | titolo | voto ----+--------+------ 1 | one | 10 2 | two | (2 rows) Can you put together a self-contained test case showing the problem? What PG version are you running, anyway? (There's a known bug in merge right join in 8.1.0-8.1.3, but AFAIR the symptom is too many output rows not too few.) regards, tom lane
