select no,sum(mileage) mileage
from(
    select no,convert(varchar(8),time,112) date,
           max(mileage) - min(mileage) mileage
    from tb
    group by no,convert(varchar(8),time,112)
) t
group by no

------解决方案--------------------
NO字段加索引 临时表是可以使用索引的