How to get two top salaries from each department

Question

select st.staff_name,st.dept_code,
st.staff_sal
from staff_master st
where staff_code in ((select  staff_code
from staff_master s
where staff_sal=(select max(staff_sal) from staff_master where dept_code=st.dept_code))
union
select staff_code from staff_master st where  staff_sal=
(select max(staff_sal) from staff_master where dept_code=st.dept_code and staff_sal < (select max(staff_sal) from staff_master where dept_code=st.dept_code)))
order by st.dept_code;

Answer 1

You can use RANK, DENSE_RANK or even ROW_NUMBER based on your need. Below is an example using DENSE_RANK. I have used EMP table available in SCOTT schema.
SQL> select * from emp order by deptno, sal desc;
     EMPNO ENAME  JOB              MGR HIREDATE         SAL        COM     DEPTNO         ID
      7782 CLARK  MANAGER         7839 09-JUN-13      12450          0         10
      7839 KING   PRESIDENT            17-NOV-13       5000          0         10
      7788 SCOTT  ANALYST         7566 19-APR-87      13000          0         20
      7369 SMITH  CLERK           7902 02-APR-13      12975          0         20
      7566 JONES  MANAGER         7839 02-APR-13      12975          0         20
      7876 ADAMS  CLERK           7788 23-MAY-87      11101          0         20
      7698 BLAKE  MANAGER         7839 01-MAY-13      12850          0         30
      7499 ALLEN  SALESMAN        7698 20-FEB-13      11600        300         30
      7844 TURNER SALESMAN        7698 08-SEP-13      11500          0         30
      7521 WARD   SALESMAN        7698 22-FEB-13      11250        500         30
      7654 MARTIN SALESMAN        7698 28-SEP-13      11250       1400         30
11 rows selected.
SQL> select *
  2    from (
  3           select e.*
  4                , dense_rank() over(partition by deptno order by sal desc) emp_rank
  5             from emp e
  6         )
  7   where emp_rank <= 2;
     EMPNO ENAME  JOB              MGR HIREDATE         SAL        COM     DEPTNO         ID   EMP_RANK
      7782 CLARK  MANAGER         7839 09-JUN-13      12450          0         10                     1
      7839 KING   PRESIDENT            17-NOV-13       5000          0         10                     2
      7788 SCOTT  ANALYST         7566 19-APR-87      13000          0         20                     1
      7369 SMITH  CLERK           7902 02-APR-13      12975          0         20                     2
      7566 JONES  MANAGER         7839 02-APR-13      12975          0         20                     2
      7698 BLAKE  MANAGER         7839 01-MAY-13      12850          0         30                     1
      7499 ALLEN  SALESMAN        7698 20-FEB-13      11600        300         30                     2
7 rows selected.
SQL>