Anton wrote:
SELECT login_id, MAX(collect_time) AS most_recent
FROM n_traffic
GROUP BY login_id
ORDER BY login_id DESC, collect_time DESC
is not so good:
=# SELECT login_id, MAX(collect_time) AS most_recent
-# FROM n_traffic
-# GROUP BY login_id
-# ORDER BY login_id DESC, collect_time DESC;
ERROR: column "n_traffic.collect_time" must appear in the GROUP BY
clause or be used in an aggregate function
If I correct this error (add collect time to GROUP BY) I'll just get
full table, sorted. And I tried to not use aggregate functions because
they make to do full table scan...
Sorry - my typo. The order-by doesn't need "collect_time" of course.
--
Richard Huxton
Archonet Ltd
