在这种情况下如何使用 T-SQL MERGE？

Question

我是 T-SQL 命令MERGE 的新手，所以我在我的 SQL 逻辑中找到了一个可以使用它的地方，并想对其进行测试，但不知道我应该如何使用它：

IF (EXISTS (SELECT 1 FROM commissions_history WHERE request = @requestID))
    UPDATE commissions_history
    SET amount = @amount
    WHERE request = @requestID
ELSE
    INSERT INTO commissions_history (amount) VALUES @amount)

请建议正确的用法。谢谢！

Answer 1

我希望它会起作用

MERGE commissions_history AS target
USING (SELECT request FROM  commissions_history WHERE request = @requestID) AS source (request)
ON (target.request = source.request)
WHEN MATCHED THEN 
    UPDATE SET amount = @amount
WHEN NOT MATCHED BY SOURCE    
    INSERT (request, amount)
    VALUES (@requestID,  @amount)

Answer 2

您查看帮助了吗？这是一个简单的例子：

MERGE dbo.commissions_history AS target
USING (SELECT @amount, @requestID) AS source (amount, request)
ON (target.request = source.request)
WHEN MATCHED THEN
    UPDATE SET amount = source.amount
WHEN NOT MATCHED THEN
    INSERT (request, amount)
    VALUES (source.request, source.amount);