（Oracle）使用插值获得第 25 个数字

Question

我的目标是获得第 25 个号码。 例如，我有 4 行，例如 3、4、5 和 7。我的目标是获得 1.25（=（4+1） 0.25）。 预期结果为 3.25，通过插值 (3+0.25 (4-3)) 获得。

我已经尝试如下。 但是还有其他有效的方法吗？

WITH DATASET AS (
SELECT 3 C1 FROM DUAL
UNION 
SELECT 4  FROM DUAL
UNION 
SELECT 5  FROM DUAL
UNION 
SELECT 7  FROM DUAL
)
SELECT 
--RNK, C1, NEXTC1-C1, FIRSTQLOCAION, FIRSTQLOCAION-RNK, C1+(NEXTC1-C1)*(FIRSTQLOCAION-RNK)
C1+(NEXTC1-C1)*(FIRSTQLOCAION-RNK)
FROM( 
SELECT C1, 
LEAD(C1, 1) OVER (ORDER BY C1) as NEXTC1 ,
RANK() OVER (ORDER BY C1) AS RNK,
((SUM(1) OVER (PARTITION BY NULL)) +1) * 0.25 AS FIRSTQLOCAION
FROM DATASET
)
WHERE
FIRSTQLOCAION>=RNK AND FIRSTQLOCAION<=RNK+1;

Answer 1

您可以使用解析 function 如下：

Select c1, 
       c1 + (
             (((Count(1) over () + 1)*0.25) - 1) * (lead(c1) over (order by c1) - c1)
            ) as calculated_number from
  From your_table t

在此解决方案中，最后一条记录将具有计算值 null，因为前导值将为 null，您必须根据您的要求调整其值。

如果您的期望是查询中的单个数字，则使用以下命令：

Select min(c1) + 
       0.25 * (min(case when rn = 2 then c1 end) 
                - min(case when rn = 1 then c1 end)) as calculated_number
from
(Select t.*,
       Row_number() over (order by c1)
  From t)

Answer 2

WITH t AS (
SELECT 3 C1 FROM DUAL
UNION 
SELECT 4  FROM DUAL
UNION 
SELECT 5  FROM DUAL
UNION 
SELECT 7  FROM DUAL
)
SELECT rn,location, calculated 
FROM ( 
Select rn, c1, 
C1 +(Count(1) over () + 1)*0.25 
-trunc( (Count(1) over () + 1)*0.25 ) *(lead(c1) over (order by c1) - c1) as calculated, --
 trunc( (Count(1) over () + 1)*0.25 ) as location --
 From (Select t.*, Row_number() over (order by c1) rn From t) ) WHERE rn=location;