Re: [SQL] Outer join in postgresql

[Robert B. Easter]

On Mon, 12 Jun 2000, Patrick Kay wrote:
> I am looking for a way run an outer join in psql.  Can anyone help?
> 
> Informix has an "OUTER" keyword.  I don't see anything like this in the docs
> for psql.
> 
> Thanks much.
> -Pat Kay

Here is an example I have about simulating an outer join in PostgreSQL:
(hope this is correct, I'm still a bit of a novice but getting better)

CREATE TABLE master (m_id INTEGER, m_name TEXT);
CREATE TABLE slave (m_id INTEGER, s_name TEXT);

INSERT INTO master (m_id, m_name) VALUES (1, 'Satan');
INSERT INTO master (m_id, m_name) VALUES (2, 'God');

INSERT INTO slave (m_id, s_name) VALUES (1, 'Joe');
INSERT INTO slave (m_id, s_name) VALUES (1, 'Tom');

SELECT * FROM master m, slave s
WHERE m.m_id = s.m_id
UNION
SELECT *, NULL, 'no slaves'
FROM master m
WHERE m.m_id NOT IN ( SELECT m_id FROM slave );

     m_id | m_name | m_id |  s_name
    ------+--------+------+-----------
        1 | Satan  |    1 | Joe
        1 | Satan  |    1 | Tom
        2 | God    |      | no slaves
    (3 rows)

    -- Oracle outer-join
    SELECT * FROM master m, slave s
    WHERE m.m_id = s.m_id (+);

     m_id | m_name | m_id |  s_name
    ------+--------+------+-----------
        1 | Satan  |    1 | Joe
        1 | Satan  |    1 | Tom
        2 | God    |      |
    (3 rows)
            

I keep a file at http://comptechnews.com/~reaster/dbdesign.html that has
some info that might be useful to some people.

-- 
Robert B. Easter