的SQL Server 2008 - 積累列

Question

我想我積累數據，你可以看到下面有源表table1：

1. 什麼是做到這一點的最好查詢？
2. 可以動態地做到這一點 - 當我添加更多類型的術語？

表1

ID | term | value 
----------------------- 
1 | I | 100 
2 | I | 200 
3 | II | 100 
4 | II | 50 
5 | II | 75 
6 | III | 50 
7 | III | 65 
8 | IV | 30 
9 | IV | 45 

而且結果應該是象下面這樣：

YTD | Acc Value 
------------------ 
I-I | 300 
I-II | 525 
I-III| 640 
I-IV | 715 

感謝

Answer 1

select 
     (select min(term) from yourtable) +'-'+term,  
     (select sum(value) from yourtable t1 where t1.term<=t.term) 
    from yourtable t 
    group by term