Mysql求每隔五分鐘一個均值

SELECT code ,datatime, Year(datatime) AS Y,Month(datatime) AS M,Day(datatime) AS d,HOUR(datatime) AS h, FLOOR(MINUTE(datatime) / 5) AS v ,
          avg(voltage2)
     from wlwdata.t_h_airelectryvalue where datatime>='2015-03-04' and code=2
GROUP BY Y,M,D,h, v    order by datatime  desc limit  100000000000000000;