hi all i hope this answer will help you


                emp
eid        ename        dep
001        manikandan   mainframe
002        karthi       java
003        jarin        mainframe
001        manikandan   java
003        jarin        testing
004        hariharan    java
001        manikandan   testing

select eid from emp e1 where 1 <
               
          (select count(*) from emp e2 where e1.eid=e2.eid)

let me know if any new answer