获取 MERGE 语句中执行的所有操作的 ROWCOUNT

Question

我对这个说法感到惊讶MERGE，该公司并没有真正实现第 2 类缓慢变化维度，但已经接近了。奇怪的是，它甚至不是分析数据，但让我们忽略这个可怕的决定。我有这个工作引用指示HashBytes的已更改行。INSERT不幸的是，为了解决所有场景，我最终在临时表的末尾 添加了实际上保存更新行的附加内容。

唉，它很实用，但如果您有更有效的设计，请分享。我会很感激。

但是，我试图row count不仅INSERT从Temp表中获取代表，而且还代表更新和新的INSERTS，所有这些都是具有自己的不同单独的操作row count，我需要记录和解释。

请问我该怎么做？

DECLARE @dtNow AS DATETIME = GetDate()
DECLARE @dtPast AS DATETIME = DATEADD(day,-1,GetDate())
DECLARE @dtFuture AS DATETIME = '22991231'
    SET NOCOUNT ON;

  -- Temp Table is JUST Updating Rows reflecting 
--Historical Marker on existing row No content change to row's columnar     content data 

IF OBJECT_ID('tempdb..#TheTempTableName') IS NOT NULL DROP TABLE     #TheTempTableName


CREATE TABLE #TheTempTableName 
(
    ABunchOfColumns
    RowCreatedDate datetime NULL,
    RowEffectiveDate datetime NULL,
    RowTerminationDate datetime NULL,
    RowIsCurrent bit NULL,
    RowHash varchar(max) NULL,
)

INSERT INTO #TheTempTableName
(
            ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 
)


SELECT
                ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 
FROM
    (
        MERGE tblDim WITH (HOLDLOCK) AS target
            USING 
            (
                SELECT          
                ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 

                FROM dbo.tblStaging
            )       
        AS source
        ON target.PKID  = source.PKID       
        WHEN MATCHED
            AND target.RowIsCurrent = 1
            AND target.RowHash != source.RowHash                    
------- PROCESS ONE -- UPDATE --- HISTORICALLY MARK EXISTING ROWS
            THEN UPDATE SET                     
                    RowEffectiveDate    =   @dtPast
                    ,RowTerminationDate =   @dtPast
                    ,RowIsCurrent   =   0                   
-----  PROCESS TWO -- INSERT ---INSERT NEW ROWS
            WHEN NOT     MATCHED                                                          
            THEN INSERT    ---   THIS INSERT Goes directly into Target ( DIM     ) Table (New Rows not matched with PK = PK ) 
                (
                ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 
                )
                VALUES
                (                   
                source.ABunchOfColumns
                    ,@dtNow                 --source.RowCreatedDate,
                    ,@dtFuture              ---source.RowEffectiveDate,
                    ,@dtFuture              ---source.RowTerminationDate,
                    ,1                      ---source.RowIsCurrent,
                    ,source.RowHash
                )
-------PROCESS THREE a  -- INSERT ---OUTPUT MATCHED ROWS FROM PROCESS ONE THAT CAUSED     HISTORICAL MARK (CHANGES) "INSERT"
        OUTPUT 
        $action Action_Out,

                ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 
    )       
    AS MERGE_OUT
WHERE MERGE_OUT.Action_Out = 'UPDATE';

----------PROCESS THREE b  -- INSERT FROM Temp Tbl to final
--Now we flush the data in the temp table into dim table

INSERT INTO tblDim
    (
                ABunchOfColumns
                ,RowCreatedDate
                ,RowEffectiveDate
                ,RowTerminationDate
                ,RowIsCurrent
                ,RowHash 
    )
SELECT
         ABunchOfColumns
        ,@dtNow AS RowCreatedDate
        ,@dtFuture AS RowEffectiveDate
        ,@dtFuture AS RowTerminationDate
        ,1 AS RowIsCurrent
        ,RowHash

FROM #TheTempTableName  
END

Answer 1

有两种类型的删除 (1) 实际删除 (2) 主键更新。所以你也可以说有两种类型的插入（1）真正的插入（2）主键更新更新总是更新。

接下来的困境是插入/删除组合何时才是真正的更新。

通常，如果您并不真正关心上面的内容，像这样的简单合并就足够了

MERGE esqlProductTarget T
USING esqlProductSource S
ON (S.ProductID = T.ProductID)
WHEN MATCHED
THEN UPDATE
     SET    T.Name = S.Name,
            T.ProductNumber = S.ProductNumber,
            T.Color = S.Color
WHEN NOT MATCHED BY TARGET
THEN INSERT (ProductID, Name, ProductNumber, Color)
     VALUES (S.ProductID, S.Name, S.ProductNumber, S.Color)
WHEN NOT MATCHED BY SOURCE
THEN DELETE
OUTPUT S.ProductID, $action into @MergeLog;

SELECT MergeAction, Cnt=count(*)
FROM   @MergeLog
GROUP BY MergeAction

输出将类似于：

+-------------+-----+--+
| MergeAction | Cnt |  |
+-------------+-----+--+
| DELETE      | 100 |  |
| UPDATE      |  60 |  |
| INSERT      |  70 |  |
+-------------+-----+--+

参考https://www.essentialsql.com/introduction-merge-statement/

我不确定为什么你有“WHERE MERGE_OUT.Action_Out = 'UPDATE'。但是如果你删除它，那么你可以获得你的行数。除非我误解了你的查询。