更正用於在DB2中標記重複行的更新查詢

Question

我試圖使用值1更新列，其中以下條件匹配。

UPDATE 
(SELECT TBL.KEY, TBL.IS_DUPLICATE FROM MYTABLE AS TBL JOIN 
(SELECT TBL1.KEY FROM MYTABLE AS TBL1 GROUP BY TBL1.KEY HAVING COUNT(TBL1.KEY)>1) SELECTION 
ON SELECTION.KEY = TBL.KEY ORDER BY TBL.KEY ASC) OuterSelection 
SET OuterSelection.IS_DUPLICATE = 1; 

這是我在運行此查詢時遇到的錯誤。

SQL錯誤[42807]：INSERT，DELETE，UPDATE，MERGE或TRUNCATE語句中的目標fullselect，視圖，類型表，物化查詢表，範圍集羣表或臨時表是其目標請求的操作是不允許的。SQLCODE = -150，SQLSTATE = 42807，DRIVER = 4.16.53

Answer 1

問題是選擇必須在WHERE子句中匹配，並且UPDATE應該只指定表。這裏是解決方案：

UPDATE TBL 
SET IS_DUPLICATE=1 
WHERE KEY IN (SELECT KEY 
FROM TBL 
GROUP BY KEY 
HAVING COUNT(*) > 1);