持之以恒

在查詢大數(shù)據(jù)量的時候，可以用TO_DATE('2011-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIAN')將數(shù)據(jù)按時間分開查詢，提高速度


select * from (
select send_time,src_id, count(*) count_
        from(
              select src_id ,to_char(send_time,'yyyymm') send_time
             from mms_mt_log 
              where send_time >= TO_DATE('2011-06-01 00:00:00', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIAN')
                    and send_time <= TO_DATE('2011-06-30 23:59:59', 'SYYYY-MM-DD HH24:MI:SS', 'NLS_CALENDAR=GREGORIAN')
                    and (sub_status = 1000 or sub_status = 4446)
                   
            )
              group by send_time, src_id
              )order by src_id

小白