从合并中捕获插入、更新和删除计数

如何解决从合并中捕获插入、更新和删除计数

我使用以下 T-sql Merge 语句将数据从事务数据库增量加载到数据仓库。此 Merge 语句将数据作为 SCD 类型 2 加载并且运行良好。

--Begin handling SCD2 changes
INSERT INTO  [DWDB].[dbo].[Dim_Warehouse]      
    (
         stg.[WarehouseID],stg.[WarehouseCode],stg.[WarehouseName]
    )   
SELECT 
         MERGE_OUT.[WarehouseID],MERGE_OUT.[WarehouseCode],MERGE_OUT.[WarehouseName]
FROM     
    (
        MERGE [DWDB].[dbo].[Dim_Warehouse] AS stg
        USING SourceDB.dbo.Warehouse AS SRC    
        ON (stg.WarehouseID = SRC.WarehouseID) 
    WHEN NOT MATCHED     
        THEN INSERT VALUES
            (
             SRC.[WarehouseID],SRC.[WarehouseCode],SRC.[WarehouseName]
            )
    WHEN MATCHED
        AND stg.dw_EndDate IS NULL
        AND 
            (
              stg.[WarehouseName]   <> src.[WarehouseName]
            ) 

        THEN
            UPDATE 
            SET  stg.dw_EndDate =  GETDATE(),stg.dw_IsCurrent = 0 
    OUTPUT $action Action_Out,SRC.[WarehouseID],SRC.[WarehouseName]
            ) AS MERGE_OUT
WHERE MERGE_OUT.Action_Out = 'UPDATE';

（为了简单起见，从上面的源代码中删除了一些列）

我最后的工作是依靠 MERGE 语句来知道有多少记录被插入、更新、删除但没有成功。

我尝试创建一个临时表并将列放在 OUTPUT 中，如以下链接所示：Sql Server 2008 MERGE - best way to get counts 和 https://www.purplefrogsystems.com/blog/2012/01/using-t-sql-merge-to-load-data-warehouse-dimensions/ 但它看起来与我的情况不同。

非常感谢您的帮助。

解决方法

为了使术语正确，@archive 是表变量，而不是临时表。（它们在很多方面都不同）。临时表看起来像这样 #archive

要解决您的问题，您可以像往常一样简单地加载到表变量中，然后从该表变量中插入。本次活动分两步进行。不需要一步完成。

另外仅供参考，根本没有必要使用合并，您可以使用单独的插入/更新语句。很多人没有意识到这一点。还要记住此 merge 问题列表。它们大多是边缘情况，但请记住还有其他选择

https://www.mssqltips.com/sqlservertip/3074/use-caution-with-sql-servers-merge-statement/

      -- Create the table variable to capture the output
      DECLARE @MergeOutput (
            Action_Out VARCHAR(100),[WarehouseID] INT,[WarehouseCode] VARCHAR(50),[WarehouseName] VARCHAR(50)
      );


        -- mere into table,capturing output into table variable
        MERGE [DWDB].[dbo].[Dim_Warehouse] AS stg
        USING SourceDB.dbo.Warehouse AS SRC    
        ON (stg.WarehouseID = SRC.WarehouseID) 
        WHEN NOT MATCHED     
        THEN INSERT VALUES
            (
             SRC.[WarehouseID],SRC.[WarehouseCode],SRC.[WarehouseName]
            )
    WHEN MATCHED
        AND stg.dw_EndDate IS NULL
        AND 
            (
              stg.[WarehouseName]   <> src.[WarehouseName]
            ) 

        THEN
            UPDATE 
            SET  stg.dw_EndDate =  GETDATE(),stg.dw_IsCurrent = 0 
    OUTPUT $action Action_Out,SRC.[WarehouseID],SRC.[WarehouseName]
    INTO @MergeOutput

-- Perform insert based on table variable
INSERT INTO  [DWDB].[dbo].[Dim_Warehouse]      
    (
         [WarehouseID],[WarehouseCode],[WarehouseName]
    )   
SELECT 
         [WarehouseID],[WarehouseName]
FROM @MergeOutput
WHERE Action_Out = 'UPDATE';