[PeterWoe]

Aus den PostgreSQL FAQ:

PostgreSQL 7.1 and later supports outer joins using the SQL standard syntax. Here are two examples:

SELECT *
FROM t1 LEFT OUTER JOIN t2 ON (t1.col = t2.col);

or
SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col);

These identical queries join t1.col to t2.col, and also return any unjoined rows in t1 (those with no match in t2). A RIGHT join would add unjoined rows of t2. A FULL join would return the matched rows plus all unjoined rows from t1 and t2. The word OUTER is optional and is assumed in LEFT, RIGHT, and FULL joins. Ordinary joins are called INNER joins.

In previous releases, outer joins can be simulated using UNION and NOT IN. For example, when joining tab1 and tab2, the following query does an outer join of the two tables:



SELECT tab1.col1, tab2.col2
FROM tab1, tab2
WHERE tab1.col1 = tab2.col1
UNION ALL
SELECT tab1.col1, NULL
FROM tab1
WHERE tab1.col1 NOT IN (SELECT tab2.col1 FROM tab2)
ORDER BY col1

Peter