sql - DB2 中是否存在 `when not matched by source`？

Question

在 SQL Server 2008 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 并且对于表中存在但不在查询中的任何记录数据时，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。根据此处的文档(http://www.ibm.com/support/knowledgecenter/SSEPGG_9.7.0/com.ibm.db2.luw.sql.ref.doc/doc/r0010873.html):

NOT MATCHED Indicates the operation to be performed on the rows where the ON search condition is false or unknown. Only INSERT or signal-statement can be specified after THEN.

因此，如果执行了 NOT MATCHED 条件，则不能使用 DELETE 命令。您可能需要执行单独的查询来删除不符合合并条件的数据。