sum(score)/datediff(hour, startdate, enddate)/24.0
select id,sum(id) over (order by 排序字段) / count(id) over (order by 排序字段)from (select 1 id,1 排序字段union all select 2,2union all select 3,3union all select 2,4) t
有平均值函数的avg(a1+a2+a3)