oracle - 防止在 Oracle 中运行总计变为负数

Question

“金额”列在第一行的值为 5，在第二行的值为 -10。

有没有办法让 oracle 的 sum(amount) over() 函数在第二行返回 0 而不是 -5？

Answer 1

公然使用 Rajesh Chamarthi 的示例来源：但改变以显示更多的负面和正面......并展示一个案例如何将所有负面改变为零，同时保持其他数量......

with t as (
  select 5 as x, 1 as id from dual
  union all
  select -10, 2 as id from dual
  union all
  select 7, 3 as id from dual
  union all
  select -5, 4 as id from dual
  union all
  select -2, 5 as id from dual
),  
B as (select  t.x, 
        case when sum(x) over (order by id) < 0 then 0 
              else sum(x) over (order by id) 
        end Amount
 from t
 order by id)
 Select X, Case when amount < 0 then 0 else amount end as Amount from B;

  T   Amount
  5      5
-10      0
  7      2
 -5      0
 -2      0

----尝试2（第一次尝试保留为下面的评论引用它）

当数量低于 0 时，我无法弄清楚如何中断窗口函数以将值重置为 0...所以我使用了递归 CTE，它给了我更大的控制权。

如果 id 不是连续的，我们可以添加一个 row_Number，这样我们就有了一个可以加入的 ID……或者我们可以使用 min() where > oldID。我假设我们有一个唯一键的唯一 ID，或者按照您希望总和发生的顺序对记录进行“排序”...

with aRaw as (
  select 5 as x, 15 as id from dual
  union all
  select -10, 20 as id from dual
  union all
  select 7, 32 as id from dual
  union all
  select 2, 46 as id from dual
  union all
  select -15, 55 as id from dual
  union all
  select 3, 68 as id from dual
),
t as (Select A.*, Row_number() over (order by ID) rn from aRAW A),

CTE(RN, ID, x, SumX) AS (
Select T.RN, T.ID, x, X from t WHERE ID = (Select min(ID) from t)
UNION ALL
Select T.RN, T.ID, T.X, case when T.X+CTE.SumX < 0 then 0 else T.X+Cte.sumX end from T
INNER JOIN CTE
 on  CTE.RN+1=T.RN)

Select * from cte;

.

1. CTE：ARaw 只是一个样本数据集
2. CTE：T 添加一个连续的行号，以防 ID 中存在间隙，从而允许在递归 CTE 上使用更简单的连接方法。
3. CTE：CTE 是递归 CTE，它保持一个运行总计，并有一个 case 语句在运行总计低于 0 时将其重置为 0

Answer 2

您可以使用 case 语句，但这不是真正的运行总计

with t as (
  select 5 as x, 1 as id from dual
  union all
  select -10, 2 as id from dual
  union all
  select 20, 3 as id from dual
  union all
  select 30, 4 as id from dual
  union all
  select 10, 5 as id from dual
)  
select  t.x, 
        case when sum(x) over (order by id) < 0 then 0 
              else sum(x) over (order by id) 
        end running_total
 from t
 order by id;

X   RUNNING_TOTAL

5   5
-10 0
20  15
30  45
10  55