根据 SQL 服务器 table 中存在的行号将项目排到列中

Question

我在 SQL 服务器 table 中有一组车辆故障部件，如下所示：

Vehicle_ID	Failed Part	RowNumber
1	0001	1
1	0002	1
1	0003	1
1	0001	2
1	0006	2
1	0007	2
1	0001	3
1	0009	3
2	0001	1
2	0002	1
2	0003	2
2	0007	2
3	0006	1
3	0007	1
4	0011	1
4	0015	1
4	0016	1

RowNumber 是我们必须定义行的列。结果 table 如下所示。 failed part 列计数的最大值为 5。

Vehicle_ID	Failed Part1	Failed Part2	Failed Part3
1	0001	0002	0003
1	0001	0006	0007
1	0001	0009
2	0001	0002
2	0003	0007
3	0006	0007
4	0011	0015	0016

我尝试了下面的语句，但无法得出准确的结果。

WITH cte AS 
(
    SELECT 
        *, 
        ROW_NUMBER() OVER (PARTITION BY Vehicle_ID,RowNumber)
                           ORDER BY [Failed Part]) rn
    FROM 
        VehicleTable
)
SELECT
    Vehicle_ID,
    MAX(CASE WHEN rn = 1 THEN [Failed Part] END) AS FailedPart1,
    MAX(CASE WHEN rn = 2 THEN [Failed Part] END) AS FailedPart2,
    MAX(CASE WHEN rn = 3 THEN [Failed Part] END) AS FailedPart3,
    MAX(CASE WHEN rn = 4 THEN [Failed Part] END) AS FailedPart4,
    MAX(CASE WHEN rn = 5 THEN [Failed Part] END) AS FailedPart5
FROM 
    cte 
GROUP BY
    Vehicle_ID

Answer 1

您代码中的问题非常微妙。您正在做的是在 Vehicle_ID 上分组，问题是输出 table 中每个 Vehicle_ID 有不止一行。相反，您应该做的是通过对您在 cte 中计算的列号 rn 进行分组来修复它：

WITH cte AS (
    SELECT *, ROW_NUMBER() OVER (PARTITION BY Vehicle_ID, RowNumber
                                 ORDER BY [Failed Part]) rn
    FROM VehicleTable
)
SELECT
    Vehicle_ID,
    MAX(CASE WHEN rn = 1 THEN [Failed Part] END) AS FailedPart1,
    MAX(CASE WHEN rn = 2 THEN [Failed Part] END) AS FailedPart2,
    MAX(CASE WHEN rn = 3 THEN [Failed Part] END) AS FailedPart3,
    MAX(CASE WHEN rn = 4 THEN [Failed Part] END) AS FailedPart4,
    MAX(CASE WHEN rn = 5 THEN [Failed Part] END) AS FailedPart5
FROM cte 
GROUP BY
    Vehicle_ID, rn

如果您希望您的行按照输出中的顺序排列，您只需在末尾添加 ORDER BY Vehicle_ID, rn。

试试看 here.

根据 SQL 服务器 table 中存在的行号将项目排到列中

Row items into column based on row number present in SQL Server table

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