更正用于在DB2中标记重复行的更新查询

Question

我正在尝试更新值为1的列，其中以下条件匹配。

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;

以下是运行此查询时出现的错误。

SQL错误[42807]：INSERT，DELETE，UPDATE，MERGE或TRUNCATE语句中的目标全查询，视图，类型表，具体化查询表，范围集群表或登台表是不允许请求的操作.. SQLCODE = -150，SQLSTATE = 42807，DRIVER = 4.16.53

Answer 1

问题是必须在WHERE子句中匹配选择，UPDATE应该只指定表。这是解决方案：

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