SQL循環求和 - MS-SQL Server / 基础类

請求幫忙.
表中有gltr_eff_dt,跟gltr_amt 兩個字段,

gltr_eff_dt gltr_amt
2000/01/01 1
2000/01/02 3
2000/01/03 -1
2000/01/04 1
2000/01/05 8
2000/01/06 -5
.
.
.
.
2010/04/30 10

   
我想循環得到下表一個結果,


year(gltr_eff_dt) month(gltr_eff_dt) sum(gltr_amt)
2000 1 100
2000 2 110
.
.
.

2010 4 120


條件是 gltr_eff_dt <= 年.月 的所有gltr_amt的和

謝謝

---

SQL code:
select year(gltr_eff_dt)[year],
month(gltr_eff_dt)[month],
(select sum(gltr_amt)
from tb
where convert(varchar(7),gltr_eff_dt,120)<convert(varchar(7),t.gltr_eff_dt,120))
from tb t

---

SQL code:
select year(gltr_eff_dt)[year],
month(gltr_eff_dt)[month],
(select sum(gltr_amt)
from tb
where convert(varchar(7),gltr_eff_dt,120)<convert(varchar(7),t.gltr_eff_dt,120))
from tb t
group by year(gltr_eff_dt),month(gltr_eff_dt)

---

引用

SQL code
select year(gltr_ef