Hello,
I need to remove duplicates rows from a subquery but order these
results by a column what is not selected. There are logically two
solutions but no works.
SELECT DISTINCT sub.foo FROM (SELECT ...) AS sub ORDER BY sub.bar
ERROR: for SELECT DISTINCT, ORDER BY expressions must appear in select list
SELECT sub.foo FROM (SELECT ...) AS sub GROUP BY sub.foo ORDER BY sub.bar
ERROR: column "sub.bar" must appear in the GROUP BY clause or be used
in an aggregate function
Does anybody know how to remove duplicate rows from a subquery and order
these results by a column what is not selected but exists in a subquery?
Thanks for any advice,
J.N.
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TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
