select * from (
SELECT
object_id,created,
max(created) as Created_date,
max(closed) as Closed_date,
max(est_duedate) as Due_date,
FROM report_tbl p GROUP BY object_id)A where Location like
'%Hubli%'
and created BETWEEN '2018-12-01' AND '2018-12-31';
в приведенном выше запросе, как использовать datediff в max () для получения разницы между датами