HOW TO GET TOP N RECORDS IN SQL , URGENT

Question

Hi,
I want to get the TOP 2 and BOTTOM 2 records (TOP 2 SAL , BOTTOM 2 SAL) from the following query result for each department . How do I get it using a SQL statement ? Thanks
SQL> SELECT A.DNAME, B.ENAME, B.SAL FROM DEPT A, EMP B WHERE A.DEPTNO = B.DEPTNO ORDER BY DNAME, SAL
DNAME------------ENAME--------SAL
ACCOUNTING-------KING--------5000
----------------CLARK--------2450
---------------MILLER--------1300
RESEARCH--------SCOTT--------3000
-----------------FORD--------3000
----------------JONES--------2975
----------------ADAMS--------1100
----------------SMITH---------800
SALES-----------BLAKE--------2850
----------------ALLEN--------1600
---------------TURNER--------1500
-----------------WARD--------1250
---------------MARTIN--------1250
----------------JAMES---------950
14 rows selected.

Answer 1

If Feroz is asking the TOP 2 Salaried employees and BOTTOM 2 Salaried employees
for ***EACH**** DEPARTMENT, then following SQL is one of the many ways(proves good with performance).Also brings top2+ bottom2 in one shot.SELECT dname, ename, sal FROM
(SELECT d.DNAME, e.ENAME, e.SAL,
       dense_rank() over(PARTITION BY e.DEPTNO ORDER BY e.SAL) dr
FROM EMP e, DEPT d
WHERE e.DEPTNO = d.DEPTNO)
WHERE dr <= 2
UNION
SELECT dname, ename, sal FROM
(SELECT d.DNAME, e.ENAME, e.SAL,
       dense_rank() over(PARTITION BY e.DEPTNO ORDER BY e.SAL DESC) dr
FROM EMP e, DEPT d
WHERE e.DEPTNO = d.DEPTNO)
WHERE dr <= 2
/Thx,
SriDHAR