如何在SQL Server中调试合并？

Question

我正在尝试学习如何使用MERGE运算符.以下代码正确编译:

    ALTER PROCEDURE moto.procPM_UpdateLines
@LineId As Int = null,
@LineName As Varchar(100),
@DeleteMe As Bit = 0
    AS
    BEGIN

    MERGE moto.tblPMLine AS line
    USING (SELECT LineId, LineName FROM moto.tblPMLine) AS existsLine
    ON line.LineId = existsLine.LineId
    WHEN MATCHED AND @DeleteMe = 1 THEN DELETE
    WHEN MATCHED AND @DeleteMe = 0 THEN UPDATE SET line.LineName = @LineName
    WHEN NOT MATCHED THEN INSERT(LineName) VALUES(@LineName);
    END
    GO

我知道这是一个非常简单的过程,但由于某种原因,当我使用以下命令时它似乎没有生成任何条目.

    execute moto.procPM_UpdateLines null, 'First test', 0

有没有办法让我知道它遵循哪个选项,如果有的话？

---

以前的存储过程已修复

   MERGE INTO moto.tblPMLine AS T
   USING (SELECT @LineId as LineId, @LineName as LineName) AS S
   ON T.LineId = S.LineId
   WHEN MATCHED AND @DeleteMe = 0 THEN --UPDATE
        UPDATE SET LineName = @LineName 
   WHEN MATCHED AND @DeleteMe = 1 THEN --DELETE
        DELETE
   WHEN NOT MATCHED THEN--INSERT
        INSERT (LineName) VALUES (@LineName)    
   OUTPUT $action AS ChangesMade;

现在它插入,更新和删除,以及返回输出.

Answer 1

您可以结合使用MERGE该OUTPUT子句来获取MERGE正在进行的某种"活动报告"(或调试"打印报表")- 这可能会帮助您了解出现问题的原因.

请参阅Adam Machanic的优秀博客文章OUTPUT博士或:我如何学会停止担心和喜欢MERGE,这表明该技术以及如何使用它

基本上它归结为使用OUTPUT带有MERGE语句的子句来获取有关正在发生的事情的信息 - 大致类似于:

MERGE INTO ......
WHEN MATCHED THEN
    .......
WHEN NOT MATCHED THEN
    ......
WHEN NOT MATCHED BY SOURCE THEN
    ........
OUTPUT
    $action AS dml_action,
    inserted.x AS new_x,
    deleted.x AS old_x,
    inserted.y AS new_y,
    deleted.y AS old_y;