SQL 计算月累计的两个方法

Part1:求累加和
-- 方法一：sum() over函数
select month_id,sum(num) over(order by month_id)
from public.test_sum_over;

-- 方法二：列子查询
select month_id
,(select sum(num) from public.test_sum_over t2 where t2.month_id<=t1.month_id)
from public.test_sum_over t1