oracle - Oracle 解析函数

Question

我有类似的问题。谁能给我解决方案。下面是表值

    10    
    20    
    30   
    40

我想要这样的输出

10  10-2     8    
20  20-8    12    
30  30-12   18    
40  40-18   22   

第一个记录按升序排序并始终减去 2，并将结果用于后续记录。

Answer 1

SQL小提琴

Oracle 11g R2 模式设置：

CREATE TABLE TEST ( VAL ) AS
          SELECT 10 FROM DUAL
UNION ALL SELECT 20 FROM DUAL
UNION ALL SELECT 30 FROM DUAL
UNION ALL SELECT 40 FROM DUAL;

查询 1：

WITH Parities AS (
  SELECT VAL,
         MOD( ROW_NUMBER() OVER ( ORDER BY VAL ), 2 ) AS Parity
  FROM   TEST
)
SELECT VAL,
       ABS( SUM( CASE PARITY WHEN 1 THEN -VAL ELSE VAL END ) OVER ( ORDER BY VAL ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW ) + 2 ) AS total
FROM   Parities

结果：

| VAL | TOTAL |
|-----|-------|
|  10 |     8 |
|  20 |    12 |
|  30 |    18 |
|  40 |    22 |

Answer 2

为了完整性 - 基本的递归解决方案：

^SQLFiddle

with t(val, n) as (
  select val, val-2 from test where val = 10
  union all select test.val, test.val-n from test, t where test.val = t.val + 10 )
select * from t