**create table emp1 as select * from emp;
insert into emp1 select * from emp1 where deptno=30;**

1、查询 表中是否含有重复的数据
select count(*),empno from emp1 group by empno having count(*)>=2;
2、查找表中重复数据

select * from emp1 where empno in (select empno from emp1 group by empno having count(empno) > 1) order by 1;

3、通过rowid查找出需要去除的重复数据
select empno,min(rowid) from emp1 group by empno having count(empno)>1;

4、删除重复数据库(通过rowid或empno )
方法一：
delete from emp1 where
rowid in
(select min(rowid) from emp1 group by empno having count(empno)>1);
方法二：
delete from emp1 where
empno in
(select empno from emp1 group by empno having count(empno)>1)
and
rowid not in

(select min(rowid) from emp1 group by empno having count(empno)>1);

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ITPub博客

Oracle 重复数据处理

**create table emp1 as select * from emp;
insert into emp1 select * from emp1 where deptno=30;**

最新文章

ITPub博客

Oracle 重复数据处理

create table emp1 as select * from emp; insert into emp1 select * from emp1 where deptno=30;

最新文章

**create table emp1 as select * from emp;
insert into emp1 select * from emp1 where deptno=30;**