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我使用下面的 T-SQL Merge 语句来执行从事务数据库到数据仓库的增量加载数据。此 Merge 语句将数据加载为 SCD 类型 2，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.[WarehouseCode]
            ,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、删除但不成功。

我试图创建一个临时表并将列放在输出中，因为这些链接表明：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。

非常感谢您的任何帮助。

4

1 回答 1

1

只是为了获得正确的术语，@archive是一个表变量，而不是一个临时表。（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。此活动分为两个步骤。它不需要一步完成。

另外仅供参考，根本不需要使用合并，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。还要记住这个问题列表merge。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.[WarehouseCode]
            ,SRC.[WarehouseName]
    INTO @MergeOutput

-- Perform insert based on table variable
INSERT INTO  [DWDB].[dbo].[Dim_Warehouse]      
    (
         [WarehouseID]
        ,[WarehouseCode]
        ,[WarehouseName]
    )   
SELECT 
         [WarehouseID]
        ,[WarehouseCode]
        ,[WarehouseName]
FROM @MergeOutput
WHERE Action_Out = 'UPDATE';
于 2021-07-07T05:33:40.040 回答