(PostgreSQL 9.something में परीक्षण किया गया)
छुटकारा और टाइमस्टैम्प की पहचान करें।
select rid, max(timestamp) as ts
from test
group by rid;
1 2011-04-14 18:46:00
2 2011-04-14 14:59:00
इसमें शामिल हों।
select test.pid, test.cost, test.timestamp, test.rid
from test
inner join
(select rid, max(timestamp) as ts
from test
group by rid) maxt
on (test.rid = maxt.rid and test.timestamp = maxt.ts)
