josep porres escreveu:
maybe this?
select value, max(id) as id, max(order_field) as order_field
from mytable
group by value
order by 3
Wrong. For the op data you will obtain tuples not in original relation.
bdteste=# SELECT * FROM foo;
id | value | order_field
----+-------+-------------
1 | 10 | 3
2 | 12 | 4
3 | 10 | 1
4 | 5 | 8
5 | 12 | 2
(5 registros)
bdteste=# SELECT max(id), value, max(order_field)
FROM foo GROUP BY value
ORDER BY 3;
max | value | max
-----+-------+-----
3 | 10 | 3
5 | 12 | 4
4 | 5 | 8
(3 registros)
Try:
bdteste=# SELECT * FROM (
SELECT DISTINCT ON (value) id, value, order_field
FROM foo ORDER BY value, order_field) AS bar
ORDER BY order_field;
id | value | order_field
----+-------+-------------
3 | 10 | 1
5 | 12 | 2
4 | 5 | 8
(3 registros)
Osvaldo
--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
