join 自连接应用于累计求和

create table dbo.FinanceMonth
(
   MonthNum int ,
   quantity int
)

;with cte as
(
    select 1 as MonthNum,100 as quantity
    union all
    select MonthNum+1,quantity+100
    from cte
    where MonthNum<12
)
insert into dbo.FinanceMonth
select *
from cte

select a.MonthNum,sum(b.quantity) as TotalQuantity
from dbo.FinanceMonth a
inner join dbo.FinanceMonth b on a.MonthNum>=b.MonthNum
group by a.MonthNum
order by a.MonthNum