解决方案1）

Question

我正在Oracle中测试一些东西并用一些示例数据填充表格，但是在这个过程中我意外地加载了重复记录，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);

column1，column2和column3构成每条记录的识别密钥。您可以列出所有列。

Answer 2

来自Ask Tom

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);

（修复了缺失的括号）

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

将表t2创建为选择distinct *来自t1;

Answer 7

要选择重复项，只能查询格式：

SELECT GroupFunction(column1), GroupFunction(column2),..., 
COUNT(column1), column1, column2...
FROM our_table
GROUP BY column1, column2, column3...
HAVING COUNT(column1) > 1

因此，根据其他建议的正确查询是：

DELETE FROM tablename a
      WHERE a.ROWID > ANY (SELECT b.ROWID
                             FROM tablename b
                            WHERE a.fieldname = b.fieldname
                              AND a.fieldname2 = b.fieldname2
                              AND ....so on.. to identify the duplicate rows....)

此查询将保留数据库中最早的记录，用于WHERE CLAUSE中选择的条件。

Oracle认证助理（2008年）

Answer 8

你应该使用游标for循环执行一个小的pl / sql块，并删除你不想保留的行。例如：

declare
prev_var my_table.var1%TYPE;

begin

for t in (select var1 from my_table order by var 1) LOOP

-- if previous var equal current var, delete the row, else keep on going.
end loop;

end;

Answer 9

使用rowid -

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

使用自我加入 -

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

Answer 10

解决方案4）

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

Answer 11

<强> 1。溶液

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

<强> 2。 SLOUTION

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
               );

3.solution

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

<强> 4。溶液

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

Answer 12

<强> 5。溶液

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

Answer 13

DELETE from table_name where rowid not in (select min(rowid) FROM table_name group by column_name);

您还可以用其他方式删除重复记录

DELETE from table_name a where rowid > (select min(rowid) FROM table_name b where a.column=b.column);

Answer 14

DELETE FROM tableName  WHERE ROWID NOT IN (SELECT   MIN (ROWID) FROM table GROUP BY columnname);

Answer 15

delete from dept
where rowid in (
     select rowid
     from dept
     minus
     select max(rowid)
     from dept
     group by DEPTNO, DNAME, LOC
);

Answer 16

真正大桌子的最快方式

创建具有以下结构的异常表： exceptions_table

ROW_ID ROWID
OWNER VARCHAR2(30)
TABLE_NAME VARCHAR2(30)
CONSTRAINT VARCHAR2(30)

尝试创建一个唯一的约束或主键，重复项将违反该约束。您将收到错误消息，因为您有重复项。例外表将包含重复行的rowid。
```
alter table add constraint
unique --or primary key
(dupfield1,dupfield2) exceptions into exceptions_table;
```

通过rowid和删除重复

，使用exceptions_table加入您的表

delete original_dups where rowid in (select ROW_ID from exceptions_table);

如果要删除的行数很大，则创建一个新表（包含所有授权和索引），使用rowid反例例连接exceptions_table，并将原始表重命名为original_dups表，并将new_table_with_no_dups重命名为原始表< / p>
```
create table new_table_with_no_dups AS (
    select field1, field2 ........ 
    from original_dups t1
    where not exists ( select null from exceptions_table T2 where t1.rowid = t2.row_id )
)
```

Answer 17

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

Answer 18

检查以下脚本 -

1

Create table test(id int,sal int);

2。

    insert into test values(1,100);    
    insert into test values(1,100);    
    insert into test values(2,200);    
    insert into test values(2,200);    
    insert into test values(3,300);    
    insert into test values(3,300);    
    commit;

3

 select * from test;

你会在这里看到6条记录 4.run低于查询 -

delete from 
   test
where rowid in
 (select rowid from 
   (select 
     rowid,
     row_number()
    over 
     (partition by id order by sal) dup
    from test)
  where dup > 1)

select * from test;

您将看到已删除重复记录希望这能解决您的疑问。谢谢:)

Answer 19

我没有看到任何使用公用表表达式和窗口函数的答案。这是我最容易使用的。

DELETE FROM
 YourTable
WHERE
 ROWID IN
    (WITH Duplicates
          AS (SELECT
               ROWID RID, 
               ROW_NUMBER() 
               OVER(
               PARTITION BY First_Name, Last_Name, Birth_Date)
                  AS RN
               SUM(1)
               OVER(
               PARTITION BY First_Name, Last_Name, Birth_Date
               ORDER BY ROWID ROWS BETWEEN UNBOUNDED PRECEDING 
                                       AND UNBOUNDED FOLLOWING)
                   AS CNT
              FROM
               YourTable
              WHERE
               Load_Date IS NULL)
     SELECT
      RID
     FROM
      duplicates
     WHERE
      RN > 1);

要注意的事项：

1）我们只检查分区子句中字段的重复。

2）如果您有理由选择一个副本而不是其他副本，您可以使用order by子句使该行具有row_number（）= 1

3）您可以通过将最终的where子句更改为＆＃34;更改保留的数字副本;其中RN＆gt; N'＃34; N> = 1（我以为N = 0会删除所有有重复的行，但它会删除所有行）。

4）在CTE查询中添加了Sum分区字段，该查询将使用组中的数字行标记每一行。因此，要选择具有重复项的行，包括第一项使用＆＃34; WHERE cnt＆gt; 1＆＃34;

Answer 20

This blog post 对于一般情况非常有帮助：

<块引用>

如果行完全复制（所有列中的所有值都可以有副本），则没有列可以使用！但是要保留一个，您仍然需要为每个组中的每一行提供一个唯一标识符。幸运的是，Oracle 已经有了一些您可以使用的东西。行号。 Oracle 中的所有行都有一个 rowid。这是一个物理定位器。也就是说，它说明 Oracle 在磁盘上存储行的位置。这对每一行都是独一无二的。因此，您可以使用此值来识别和删除副本。为此，请将不相关删除中的 min() 替换为 min(rowid)：

delete films
where  rowid not in (
  select min(rowid)
  from   films
  group  by title, uk_release_date
)

Answer 21

解决方案：

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
);

Answer 22

为了获得最佳表现，这是我写的：
（见执行计划）

DELETE FROM your_table
WHERE rowid IN 
  (select t1.rowid from your_table  t1
      LEFT OUTER JOIN (
      SELECT MIN(rowid) as rowid, column1,column2, column3
      FROM your_table 
      GROUP BY column1, column2, column3
  )  co1 ON (t1.rowid = co1.rowid)
  WHERE co1.rowid IS NULL
);

Answer 23

create or replace procedure delete_duplicate_enq as
    cursor c1 is
    select *
    from enquiry;
begin
    for z in c1 loop
        delete enquiry
        where enquiry.enquiryno = z.enquiryno
        and rowid > any
        (select rowid
        from enquiry
        where enquiry.enquiryno = z.enquiryno);
    end loop;
 end delete_duplicate_enq;

从Oracle中删除表中的重复行

23 个答案:

解决方案1）

解决方案2）

解决方案3）

解决方案4）