Create & Select Department

CREATE TABLE dept (deptid int, deptname VARCHAR(10));
INSERT INTO dept VALUES(1,'HR');
INSERT INTO dept VALUES(2,'IT');
INSERT INTO dept VALUES(3,'Finance');
COMMIT;

SELECT * FROM (
SELECT deptname,ename,salary,ROW_NUMBER() over(PARTITION BY deptname ORDER BY salary DESC) rn
FROM emp_big e , dept d
WHERE e.deptid=d.deptid
)  t WHERE rn<=5;