How can i fetch duplicate data's from a table?

Expecting EMPNO is essential/primary key and ENAME has duplicate values then you can use following SQL.

select ENAME from EMPLOYEE group by ENAME having count(ENAME) > 1;

SELECT column_name 

FROM tablename

GROUP BY column_name 

HAVING COUNT(column_name ) > 1

select column1, column2..., count(columnlast)

from table_name

where (all_conditions_if_required)

group by columnlast ------ (if it is the comlumn with duplicate data)

having count(columnlast) > 1 ;

In order to find the duplicate data from the table you can use the below query.

select empno,ename,sal,job,dept from employee

group by empno,ename,sal,job,dept from employee having count(1) > 1.

We have other methods also using analytical function, but this is easiest u can use.

You can use HAVING keyword along with GROUP BY. For example,

SELECT *

FROM tablename

GROUP BY fieldname1

HAVING COUNT(fieldname1) > 1

fieldname1 is the name of the column that contain duplicate values. 

select distinct * from employee;

select * from Employee group by empno,ename, sal, job, deptno having count(*)>1;

select * from employee where rowid not in (select min(rowid) from emloyee group by empno);

 SELECT ROWID,empno,ename,sal,job,deptno

   FROM employee mq

  WHERE mq.ROWID > ANY( SELECT csq.ROWID

                       FROM employee csq

                      WHERE csq.empno = mq.empno

                        AND csq.ename = mq.ename

                        AND csq.sal   = mq.sal

                        AND csq.job   = mq.job

                        AND csq.deptno = mq.deptno );

select EMPNO, ENAME, SAL, JOB, DEPTNO from employee group by EMPNO, ENAME, SAL, JOB, DEPTNO having count(*)>=2;