Question

我有一张这样的表：

Loan_Num asset LTV
1         20    0.2
2         20    0.2
3         20    0.12 
4         20    0.2
5         10    0.3
6         10    0.3
7         10    0.22 
8         10    0.3

我想通过资产组为此表添加一个公共值。

Loan_Num asset LTV   cV
1         20    0.2  0.2
2         20    0.2  0.2
3         20    0.12 0.2
4         20    0.2  0.2
5         10    0.3  0.3
6         10    0.3  0.3
7         10    0.22 0.3
8         10    0.3  0.3

有任何建议如何做到这一点？是否存在共同价值的内置函数？

Answer 1

这样做的一种方法是

WITH CTE1
     AS (SELECT *,
                COUNT(*) OVER (PARTITION BY [asset], [LTV]) AS C
         FROM   YourTable),
     CTE2
     AS (SELECT *,
                RANK() OVER (PARTITION BY [asset] ORDER BY C DESC, [LTV] DESC) AS R
         FROM   CTE1)
SELECT [Loan_Num],
       [asset],
       [LTV],
       MAX(CASE
             WHEN R = 1
               THEN [LTV]
           END) OVER (PARTITION BY [asset]) AS cV
FROM   CTE2

Demo

虽然实际上这会更有效，因为它会删除排序

WITH CTE1
     AS (SELECT *,
                COUNT(*) OVER (PARTITION BY [asset], [LTV]) AS C
         FROM   YourTable),
     CTE2
     AS (SELECT *,
                MAX(C) OVER (PARTITION BY [asset]) AS MaxC
         FROM   CTE1)
SELECT [Loan_Num],
       [asset],
       [LTV],
       MAX(CASE
             WHEN C = MaxC
               THEN [LTV]
           END) OVER (PARTITION BY [asset]) AS cV
FROM   CTE2

找到分区的公共值

1 个答案: