合并-有条件的“淲匹配然后更新”。

Question

下图中的高亮显示了我要实现的逻辑。我意识到语法不正确。

只有在目标表中其列之一的值为空且源表中的对应值不为空的情况下，才可以有条件地更新MERGE语句中的记录吗？

您如何建议重写？

MERGE dbo.input_311 AS [t]
USING dbo.input_311_staging AS [s]
ON ([t].[unique key] = [s].[unique key])
WHEN NOT MATCHED BY TARGET
    THEN INSERT(t.[Created Date]) VALUES(s.[Created Date])
WHEN MATCHED
    THEN UPDATE SET(t.[Created Date] = s.[Created Date]
                WHERE s.[Created Date] IS NOT NULL
                AND t.[Created Date] IS NULL)
OUTPUT deleted.*, $action, inserted.*;
GO

Answer 1

您也许可以使用When Matched And (s.[Created Date] Is Not Null And t.[Created Date] Is Null) Then Update ...。