sql-server - SQL Server 合并语句

Question

我正在我的存储过程中执行合并语句。我需要在更新和插入期间计算行数。如果我使用公共(public)变量来获取更新的行(对于更新和插入)我有什么不同，这是我从更新中获得的计数，这是我从插入中获得的计数。请给我一个更好的方法

Answer 1

您可以创建一个表变量来保存操作类型，然后向其OUTPUT伪$action列。

示例

/*Table to use as Merge Target*/
DECLARE @A TABLE (
 [id] [int] NOT NULL PRIMARY KEY CLUSTERED,
 [C] [varchar](200) NOT NULL)

/*Insert some initial data to be updated*/
 INSERT INTO @A
 SELECT 1, 'A' UNION ALL  SELECT 2, 'B'

/*Table to hold actions*/
 DECLARE @Actions TABLE(act CHAR(6))

/*Do the Merge*/ 
   MERGE @A AS target
    USING (VALUES (1, '@a'),( 2, '@b'),(3, 'C'),(4, 'D'),(5, 'E')) AS source (id, C)
    ON (target.id = source.id)
       WHEN MATCHED THEN 
        UPDATE SET C = source.C 
    WHEN NOT MATCHED THEN    
        INSERT (id, C)
        VALUES (source.id, source.C)
    OUTPUT $action INTO @Actions;

   /*Check the result*/ 
    SELECT act, COUNT(*) AS Cnt
    FROM @Actions
    GROUP BY act

返回

act    Cnt
------ -----------
INSERT 3
UPDATE 2