"Running Total" SQL 查询并使用自定义第一个值开始此过程

Question

我想用一些号码开始 "running total" 进程。

DECLARE @x int
SELECT @x = ...
@x = 50

这是我的 运行 总查询

SELECT 
    id, debit, credit,
    SUM(debit - credit) OVER (ORDER BY id ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal
FROM 
    TABLE

结果：

debit    credit     RunningTotal
--------------------------------
10       0          10
10       0          20
10       0          30
0        10         20

但是，我正在尝试从 @x;

开始

debit      credit     RunningTotal
-----------------------------------
50         0          50            <--- x value (@x)
10         0          60
10         0          70
10         0          80
0          10         70

我该怎么做？

谢谢。

Answer 1

将虚拟行添加到具有最小 ID 的源 table：

SELECT  debit, credit,
SUM(debit - credit) OVER (ORDER BY id ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS RunningTotal
FROM 
(select id, debit, credit from tab 
union all 
select -1 as id, @x as debit, 0 as credit) tab;