sql中over用法

累加当日、昨日、明日：

select a,b,sum(c) over(partition by a order by b rows between 1 preceding and 1 following） from t

累加当日和昨天：
select a,b,sum(c) over(partition by a order by b rows between 1 preceding and current row) from t

累加历史：分区内当天及之前所有
select a,b,sum(c) over(partition by a order by b) from t
或者：
select a,b,sum(c) over(partition by a order by b rows between unbounded preceding and current row) from t

累加分区内所有：当天和之前之后所有

select a,b,sum(c) over(partition by a order by b rows between unbounded preceding and unbounded following) from t