On 28 October 2016 at 21:39, Guyren Howe <guyren@gmail.com> wrote:
Using 9.5, this query:
SELECT o.id, a.numberAS awb FROM pt.orders o LEFT JOIN ( SELECT DISTINCT ON ((string_agg(air_way_bills.number::text, ','::text))) string_agg(air_way_bills.number::text, ','::text) AS number, air_way_bills.order_id FROM pt.air_way_bills GROUP BY air_way_bills.order_id) a ON a.order_id = o.id
The DISTINCT ON expression(s) must match the leftmost ORDER BY expression(s). The ORDER BY clause will normally contain additional expression(s) that determine the desired precedence of rows within each DISTINCT ON group.