On 1 December 2011 13:16, Amitabh Kant <amitabhkant@xxxxxxxxx> wrote: > I am trying (through conditional left join?) to fetch all records of tbldata > and the operator name from tbloperators who was operating the unit at event > time. If no operator was present, it should return null. I think you want something akin to: SELECT * FROM tbldata AS a LEFT JOIN (tbloperatorschedule INNER JOIN tbloperator USING (operator_id)) AS b ON (a.unit_id = b.unit_id AND a.event_time BETWEEN b.schedule_start_time AND b.schedule_end_time ) -- If you can't see the forest for the trees, Cut the trees and you'll see there is no forest. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general