SQL マージまたは UPDATE / INSERT の使用

UPDATE m SET 
  col2 = t.col2, 
  col3 = t.col3 -- etc. - all columns except Customer_Number
FROM dbo.Master_File AS m
INNER JOIN 
(
  SELECT 
    Customer_Number, rn = ROW_NUMBER() OVER
    (
      PARTITION BY Customer_Number ORDER BY [timestamp_column] DESC
    ), col2, col3, ... etc ...
  FROM dbo.Temp_Table
) AS t
ON m.Customer_Number = t.Customer_Number
WHERE t.rn = 1;

INSERT dbo.Master_File(Customer_Number, col2, col3, ...etc...)
  SELECT Customer_Number, col2, col3, ...etc...
  FROM 
  (
    SELECT 
      Customer_Number, rn = ROW_NUMBER() OVER 
      (
        PARTITION BY Customer_Number ORDER BY [timestamp_column DESC
      ),
      col2, col3, ...etc...
    FROM dbo.Temp_Table AS t 
    WHERE NOT EXISTS 
    (
      SELECT 1 FROM dbo.Master_File AS m
      WHERE m.Customer_Number = t.Customer_Number
    )
  ) AS x WHERE rn = 1;

これにより、宛先にまだ存在しないソース テーブルの複数の行が処理されます。調整が必要な列名について推測しました。

MERGE 魅力的かもしれませんが、敬遠する理由がいくつかあります:

最近、警告のヒントを公開しましたここにも 他の意見をここに集めました .