Delete duplicate records from a table

1 ) Write a Query To Delete The Repeted Rows from emp table;

SQL>Delete from emp where rowid not in(select min(rowid)from emp group

by ename)

               

2) TO DISPLAY 5 TO 7 ROWS FROM A TABLE

SQL>select ename from emp

         where rowid in(select rowid from emp where rownum<=7

         minus

  select rowid from empi where rownum<5)

3)  DISPLAY  TOP N ROWS FROM TABLE?

SQL>SELECT * FROM

                (SELECT *  FROM EMP ORDER BY ENAME DESC)

                 WHERE ROWNUM <10;

4) DISPLAY   TOP 3 SALARIES FROM EMP;

SQL>SELECT SAL FROM ( SELECT  * FROM EMP ORDER  BY SAL DESC )

                   WHERE ROWNUM <4

5) DISPLAY  9th FROM THE EMP TABLE?

SQL>SELECT ENAME FROM EMP

                WHERE ROWID=(SELECT ROWID FROM EMP WHERE ROWNUM<=10

                MINUS

                SELECT ROWID FROM EMP WHERE ROWNUM <10)

                select second max salary from emp;

                select max(sal) fromemp where sal<(select  max(sal) from emp);