Question

在SQL Server 2008中的MERGE语句中存在WHEN NOT MATCHED BY SOURCE和WHEN NOT MATCHED BY TARGET，示例取自Inserting, Updating, and Deleting Data by Using MERGE

-- MERGE statement with join conditions that produce unexpected results.
USE tempdb;
GO
BEGIN TRAN;
MERGE Target AS T
USING Source AS S
ON (T.EmployeeID = S.EmployeeID AND T.EmployeeName LIKE 'S%' 
    AND S.EmployeeName LIKE 'S%' )
WHEN NOT MATCHED BY TARGET
    THEN INSERT(EmployeeID, EmployeeName) VALUES(S.EmployeeID, S.EmployeeName)
WHEN MATCHED 
    THEN UPDATE SET T.EmployeeName = S.EmployeeName
WHEN NOT MATCHED BY SOURCE
    THEN DELETE
OUTPUT $action, Inserted.*, Deleted.*;
ROLLBACK TRAN;
GO

DB2中有这样的东西吗？例如，当我执行MERGE并且表中的任何记录数据存在但不存在于查询中时，NOT MATCH BY SOURCE它将从表中删除数据。

Answer 1

我目前正在寻找类似问题的答案，据我所知，DB2不支持它。根据这里的文件（http://www.ibm.com/support/knowledgecenter/SSEPGG_9.7.0/com.ibm.db2.luw.sql.ref.doc/doc/r0010873.html）：

NOT MATCHED表示要对其中的行执行的操作 ON搜索条件为false或未知。只有INSERT或可以在那之后指定signal-statement。

因此，如果执行NOT MATCHED条件，则不能使用DELETE命令。您可能需要执行单独的查询以删除与合并条件不匹配的数据。

DB2中是否存在“当与源不匹配”时？

1 个答案: