select A.fir_time as dt, round(count(J.sec_time)/count(A.fir_time),2) as uv_left_rate from (select uid, min(date(in_time)) as fir_time from tb_user_log group by uid) as A #每日新增用户 left join (select * from (select uid, sec_time, if(@pre = uid, @rownum:=@rownum+1,@rownum:=1) as rownum, @pre:= uid from ...