Mysql按照固定时间间隔统计数据

SELECT STCD,
       DATE_FORMAT(TM, '%Y-%m-%d %08:%00:%00')    AS TM,
       SUM(DRP)                                   AS DRP,
       FLOOR(UNIX_TIMESTAMP(TM) / (24 * 60 * 60)) AS timekey
FROM st_pptn_r
WHERE stcd = #{paramCondition.stcd}
  and `TM` >= #{paramCondition.sTime}
  AND drp > 0
GROUP BY timekey;

DRP是需要统计累计的数据字段，TM是日期字段