select convert(varchar(7),时间,120)
,sum(设备1)
,sum(设备2)
,sum(设备3) 
from tb
group by convert(varchar(7),时间,120)

------解决方案--------------------

SQL code
--差


SELECT  时间, SUM(设备1), SUM(设备2), SUM(设备3)
FROM    (
          SELECT  CONVERT(VARCHAR(7), 时间, 120) AS 时间, 设备1, 设备2, 设备3
          FROM    tb AS t
          WHERE   时间 = (
                         SELECT MAX (时间) FROM tb WHERE CONVERT( VARCHAR (7), 时间, 120)= CONVERT( VARCHAR (7), t.时间, 120)
                       )
          GROUP BY CONVERT(VARCHAR(7), 时间, 120)
          UNION ALL
          SELECT  CONVERT(VARCHAR(7), 时间, 120) AS 时间, -设备1, -设备2, -设备3
          FROM    tb AS t
          WHERE   时间 = (
                         SELECT MIN (时间) FROM tb WHERE CONVERT( VARCHAR (7), 时间, 120)= CONVERT( VARCHAR (7), t.时间, 120)
                       )
          GROUP BY CONVERT(VARCHAR(7), 时间, 120)
        ) AS a
GROUP BY 时间