Why?
4.22) How do I create a column that will default to the current time?
4.23) Why are my subqueries using IN so slow?
+ 4.24) How do I do an outer join?
Extending PostgreSQL
WHERE EXISTS (SELECT col2 FROM TAB2 WHERE col1 = col2)
We hope to fix this limitation in a future release.
+
+ 4.24) How do I do an outer join?
+
+ PostgreSQL does not support outer joins in the current release. They
+ 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 tab1.col1
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Extending PostgreSQL