如何在PostgreSQL中查找和删除重复值

Question

我的逻辑是生成重复值，我需要过滤到此

中的一个值

  25-01-2018 01:12 PM 
  25-01-2018 01:12 PM 
  25-01-2018 01:12 PM
  25-01-2018 06:12 PM
  25-01-2018 06:12 PM
  25-01-2018 06:12 PM

我需要输出：

  25-01-2018 01:12 PM 
  25-01-2018 06:12 PM

它应该删除我使用的postgresql中的重复值

select a.check_in,a.check_out, b.break_reason from
                    (
                select 
                string_agg(to_char((check_in ::TIMESTAMP::VARCHAR || ' UTC')::TIMESTAMPTZ AT TIME ZONE 'Asia/kolkata','dd-mm-YYYY HH12:MI AM'),E'\n' ) as check_in,
                string_agg(to_char((check_out ::TIMESTAMP::VARCHAR || ' UTC')::TIMESTAMPTZ AT TIME ZONE 'Asia/kolkata','dd-mm-YYYY HH12:MI AM'),E'\n' ) as check_out,
                a.break_reason

                from account_analytic_line a
                inner join project_task p on a.task_id = p.id
                inner join sale_order_line sl on sl.id = p.sale_line_id
                inner join sale_order so on so.id = sl.order_id
                where  a.name = 'pause' and so.id= %s
                group by a.check_in,a.check_out,a.break_reason

                order by a.break_reason
                )a
                 right join
                (select unnest(string_to_array('Waiting for Customer Approval;Others;Waiting for Parts;Waiting for Decision;Waiting for Diagnosis',';')) as break_reason)b
                on a.break_reason = b.break_reason

                order by b.break_reason desc

这里check_in和check_out产生多个日期。我需要在这里删除重复