SQL Server：如何从每个组中获取最高的“ N”个最大出现次数

Question

我有一个下面的数据集，我正在尝试每个CID的最大出现次数 OID。

IF OBJECT_ID('TEMPDB..#SS',N'U') IS NOT NULL 
DROP TABLE #SS
GO
SELECT * INTO #SS FROM (
SELECT 1 AS OID,501 AS CID
UNION ALL
SELECT 1 AS OID,503 AS CID
UNION ALL
SELECT 1 AS OID,502 AS CID
UNION ALL
SELECT 1 AS OID,501 AS CID
UNION ALL
SELECT 1 AS OID,501 AS CID
UNION ALL
SELECT 2 AS OID,502 AS CID
UNION ALL
SELECT 2 AS OID,502 AS CID
UNION ALL
SELECT 2 AS OID,502 AS CID
UNION ALL
SELECT 2 AS OID,501 AS CID
UNION ALL
SELECT 1 AS OID,503 AS CID
)A
GO

在上面的示例数据集中，每个出现时间最多的CID需要获得2 OID。预期结果可能是：

OID CID
1   501
1   503
2   501
2   502

这不能与SQL Select top frequent records重复，因为我需要此子查询，并且SQL Server无法在子查询中接受ORDER BY，最终我需要一种排名函数来解决我的问题问题。所提供的链接中未使用排名功能。

Answer 1

您可以利用ROW_NUMBER轻松完成此操作。感谢Tab Alleman对您的要求的澄清。

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