从Oracle中删除表中的重复行

Question

我正在Oracle中测试一些东西,并用一些示例数据填充了一个表,但是在这个过程中我不小心加载了重复的记录,所以现在我无法使用某些列创建主键.

如何删除所有重复的行并只留下其中一行？

Answer 1

使用rowid伪列.

DELETE FROM your_table
WHERE rowid not in
(SELECT MIN(rowid)
FROM your_table
GROUP BY column1, column2, column3);

在哪里column1,column2并且column3构成每条记录的识别密钥.您可以列出所有列.

Answer 2

从问汤姆

delete from t
 where rowid IN ( select rid
                    from (select rowid rid, 
                                 row_number() over (partition by 
                         companyid, agentid, class , status, terminationdate
                                   order by rowid) rn
                            from t)
                   where rn <> 1);

(修正了缺失的括号)

Answer 3

来自DevX.com:

DELETE FROM our_table
WHERE rowid not in
(SELECT MIN(rowid)
FROM our_table
GROUP BY column1, column2, column3...) ;

其中column1,column2等是您要使用的键.

Answer 4

DELETE FROM tablename a
      WHERE a.ROWID > ANY (SELECT b.ROWID
                             FROM tablename b
                            WHERE a.fieldname = b.fieldname
                              AND a.fieldname2 = b.fieldname2)

Answer 5

解决方案1)

delete from emp
where rowid not in
(select max(rowid) from emp group by empno);

解决方案2)

delete from emp where rowid in
               (
                 select rid from
                  (
                    select rowid rid,
                      row_number() over(partition by empno order by empno) rn
                      from emp
                  )
                where rn > 1
               );

解决方案3)

delete from emp e1
         where rowid not in
          (select max(rowid) from emp e2
           where e1.empno = e2.empno ); 

Answer 6

从t1创建表t2作为select distinct*;