sql - 当前行的累计值 + 前一行的总和

Question

如何将表中的列转换为:

ColumnA   ColumnB
2           a
3           b
4           c
5           d
1           a

对此:

ColumnA          ColumnB
3                 a
6(=3+3)           b   
10(=4+3+3)        c   
15(=5+4+3+3)      d 

我有兴趣看看，特别是。你会选择什么方法。

Answer 1

像这样:

;WITH cte
AS
(
   SELECT ColumnB, SUM(ColumnA) asum 
   FROM @t 
   gROUP BY ColumnB

), cteRanked AS
(
   SELECT asum, ColumnB, ROW_NUMBER() OVER(ORDER BY ColumnB) rownum
   FROM cte
) 
SELECT (SELECT SUM(asum) FROM cteRanked c2 WHERE c2.rownum <= c1.rownum),
  ColumnB
FROM cteRanked c1;

这应该给你:

ColumnA    ColumnB
3             a
6             b
10            c
15            d

<小时/>

这里是a live demo