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Diffstat (limited to 'doc/FAQ')
-rw-r--r-- | doc/FAQ | 14 |
1 files changed, 8 insertions, 6 deletions
@@ -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 |