SQL服務器查詢如何與子查詢有多個列比較

Question

如何使更新查詢基於子查詢工作？
如何將子查詢中的所有這些列與update語句中的列進行比較？
有沒有一些乾淨整潔的方法來做到這一點？

我與它試圖查詢如下所示：

UPDATE Temp_CropData 
SET RecordStatus = 0, 
    Remarks = ISNULL(Remarks, '') +' Duplicate Records' 
WHERE 
    (SELECT Commodity ,City,Period,CropCondition 
     FROM [Temp_CropData] 
     GROUP BY DDate,Commodity,City,Period,CropCondition 
     HAVING count(*) >1) 

Answer 1

試試這個：

UPDATE cd 
SET RecordStatus = 0,  
    Remarks = ISNULL(Remarks, '') +' Duplicate Records' 
FROM Temp_CropData cd 
JOIN (SELECT Commodity ,City,Period,CropCondition  
FROM [Temp_CropData]   
GROUP BY DDate,Commodity,City,Period,CropCondition   
HAVING count(*) >1) dup 
    ON cd.DDate = dup.DDate AND cd.Commodity=dup.Commodity AND cd.City = dup.City 
    AND cd.Period = dup.Period AND cd.CropCondition = dup.CropCondition 

Answer 2

嘗試使用MERGE：

MERGE INTO Temp_CropData 
    USING (
      SELECT Commodity, City, Period, CropCondition 
      FROM Temp_CropData 
      GROUP 
       BY DDate, Commodity, City, Period, CropCondition 
      HAVING COUNT(*) > 1 
     ) AS source 
     ON Temp_CropData.Commodity = source.Commodity 
     AND Temp_CropData.City = source.City 
     AND Temp_CropData.Period = source.Period 
     AND Temp_CropData.CropCondition = source.CropCondition 
WHEN MATCHED THEN 
    UPDATE 
     SET RecordStatus = 0, 
      Remarks = ISNULL(Remarks, '') + ' Duplicate Records'; 

我稍微懷疑的事實，你的子查詢的SELECT和GROUP BY條款不匹配，雖然（即DDate是在GROUP BY但不是SELECT）。