Question

我有一张表Emp，有这样的记录

Id     Name
1      A
2      B
3      C
1      A
1      A
2      B
3      C

现在我想删除表中的重复行我正在使用此查询来选择或计算重复记录的数量

SELECT NameCol, COUNT(*) as TotalCount FROM TestTable 
GROUP BY NameCol HAVING COUNT(*) > 1 
ORDER BY COUNT(*) DESC

我应该写什么查询来删除表中的重复行。

如果我编写此查询以删除重复记录，那么它会给出(0) row Affected结果。

`DELETE FROM TestTable 
    WHERE ID NOT IN ( SELECT MAX(ID) FROM 
                                     TestTable 
                                     GROUP BY NameCol
                    )`

Answer 1

对于sqlserver 2005 +

TESTDATA：

declare @t table(Id int, Name char(1))
insert @t values
(1,'A'),(2,'B'),(3,'C'),(1,'A'),(1,'A'),(2,'B'),(3,'C')

删除声明（用你的Emp表替换@t）

;with a as
(
select row_number() over (partition by id, name order by id) rn
from @t
)
delete from a where rn > 1

select * from @t

Answer 2

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Answer 3

**Q How to Remove duplicate data with help of Rowid**   


create table abcd(id number(10),name varchar2(20))

insert into abcd values(1,'abc')

insert into abcd values(2,'pqr')


insert into abcd values(3,'xyz')

insert into abcd values(1,'abc')

insert into abcd values(2,'pqr')

insert into abcd values(3,'xyz')


select * from abcd

id  Name
1   abc
2   pqr
3   xyz
1   abc
2   pqr
3   xyz

Delete Duplicate record but keep Distinct Record in table 

DELETE 
FROM abcd a
WHERE ROWID > (SELECT MIN(ROWID) FROM abcd b
WHERE b.id=a.id
);

run the above query 3 rows delete 

select * from abcd

id  Name 
1   abc
2   pqr
3   xyz

从表中删除具有相同Id的重复行

3 个答案: