-- 以「年月日」分组，求sum(wait_time)即可

———了解思路，根据不同的数据库类型自行扩展！

以MySQL库为例：

-- 要求date_time是标准的日期型

SELECT

DATE_FORMAT(date_time, "%Y-%m-%d") as t,

SUM(wait_time) AS wait_time

FROM

tab_name

GROUP BY

DATE_FORMAT(date_time, "%Y-%m-%d")

select term,sum(vait_time) as wait_time_sum from (

select  convert(varchar(10),date_time,120) as term,wait_time

from tablename

) a

group by term

     sqlserver类似这样，tablename为表名。