SQL中不同行的求和值

Question

我想在SQL示例

中对来自不同行的值求和

|Period | Amount  |Sum    |
---------------------------
|201401 | 100.00  |100.00 |
|201402 | 200.00  |300.00 |
|201403 | 500.00  |800.00 |
|201404 | 300.00  |1100.00|
|201405 |  50.00  |1150.00|

基本上是按月计算到201412的值。

有什么想法吗？

Answer 1

SELECT t1.Period, SUM(t2.AMOUNT)
FROM table as t1
  JOIN table as t2
  ON t1.Period >= t2.Period
GROUP BY t1.Period