Tim Tassonis <timtas@xxxxxxxx> schrieb: > This is absolutely not what I want. I want a row for every person and every > course, regardless whether the person has taken the course or not. If the > person has not taken the course, I want a null value in the person id > column: test=# select c.id, c.name, pc.person_id from course c cross join person p left outer join person_course pc on (p.id,c.id)=(pc.person_id,pc.course_id); id | name | person_id ----+--------------+----------- 1 | SQL Beginner | 1 1 | SQL Beginner | 1 | SQL Beginner | 3 2 | SQL Advanced | 2 | SQL Advanced | 2 | SQL Advanced | 3 (6 rows) But i think, this is a little bit stupid, because row 4 and 5 are the same. Perhaps this would be better: test=# select c.id, c.name, p.id as person, pc.person_id from course c cross join person p left outer join person_course pc on (p.id,c.id)=(pc.person_id,pc.course_id); id | name | person | person_id ----+--------------+--------+----------- 1 | SQL Beginner | 1 | 1 1 | SQL Beginner | 2 | 1 | SQL Beginner | 3 | 3 2 | SQL Advanced | 1 | 2 | SQL Advanced | 2 | 2 | SQL Advanced | 3 | 3 (6 rows) Andreas -- Really, I'm not out to destroy Microsoft. That will just be a completely unintentional side effect. (Linus Torvalds) "If I was god, I would recompile penguin with --enable-fly." (unknow) Kaufbach, Saxony, Germany, Europe. N 51.05082°, E 13.56889°
