Question

假设我有一个表A列的表格如下：

a  
--
x  
y  
m  
x  
n  
y

我想删除所有具有重复列值的行，并且只保留一个值。完成此操作后，我的专栏将如下：

select distinct a from A;

我know how to select rows with repeated a column values但我不能只用DELETE替换select，因为它也会删除唯一值任何帮助将不胜感激。

Answer 1

在Oracle中，您可以使用隐藏列rowid和相关子查询来执行此操作：

delete from a
    where rowid > (select min(rowid)
                   from a a2
                   where a.a = a2.a
                  );

或者，您可以将其标记为not in：

delete from a
    where rowid not in (select min(rowid)
                        from a a2
                        group by a2.a
                       );

Answer 2

您可以结合使用CTE和Ranking function

;With cte As
(
Select ROW_NUMBER() OVER (PARTITION BY colA ORDER BY colA) as rNum
From yourTable 
)

Delete From cte
Where rNum<>1

Answer 3

在SQL中，您可以使用CTE并删除重复的行。请参阅下面的查询。

WITH CTE AS(
   SELECT a,
       RN = ROW_NUMBER()OVER(PARTITION BY a ORDER BY a)
   FROM A
)
DELETE FROM CTE WHERE RN > 1

删除具有一些重复列值的行

3 个答案: