select e.*
from employee e
where rowid > (select min(rowid) 
                 from employee b 
                where e.employee_id = b.employee_id)

delete 
  from employee 
 where rowid not in (
             select min(rowid)
               from employee 
              group by employee_id
     )

------解决方案--------------------

SQL code
select job
from (select job,row_number()over (partition by job order by job )rn
      from emp)
--要按什么删除 order by里 排下序就可以了

------解决方案--------------------
然後 我用手動的方法找到一個相同的id＝‘123’    用123這個id去查詢rowid  可是也只能查到一個rowid   可是123的數據明明是重復的   為什么呢？
--------------------------------------------------

你是如何确认这条数据明明是重复的？估计是你没有commit

------解决方案--------------------
SQL code
DELETE FROM EMPLOYEE E2
 WHERE ROWID NOT IN
       (SELECT MAX(E1.ROWID)
          FROM EMPLOYEE E1
         WHERE　E1.EMPLOYEE_ID = E2.EMPLOYEE_ID);

------解决方案--------------------
删除的方法是对的，查看有没有提交