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@@ -948,7 +948,8 @@ SELECT *
4.24) How do I do an outer join?
- PostgreSQL 7.1 and later supports outer joins. Here are two examples:
+ 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);
@@ -956,11 +957,12 @@ SELECT *
SELECT *
FROM t1 LEFT OUTER JOIN t2 USING (col);
- These identical queries join t1.col to t2.col, and return any unjoined
- rows in t1. A RIGHT join would return unjoined rows of table t2. A
- FULL join would return 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.
+ 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