Calculation of nth highest value in a Group

Question

Hi All,
I have following problem to be solved. I have a table with following structure:
Table emp
EmpID number
NAme varchar2
DeptID number
Salary numberNow for finding max salary in each dept, I can use:
select DeptId,max(salary) from emp group by DeptId;NOw to find second max salary, I can do below:
select DeptId,max(salary) from emp
where (DeptId,salary) not in (select DeptId,max(salary) salary from emp group by DeptId) group by DeptId;But suppose I need to find 5th or 6th max salary then this method will be cumbersome.
I need a SQL query in which I can dynamically pass the parameter to calculate it.
Kindly help.

Answer 1

You could try something like this:
with ranking as
   (select
       deptid,
       salary,
       row_number() over (partition by deptid order by salary desc) rn
    from
       emp)
select
   deptid,
   salary
from
   rankings
where
   rn=4;This should get the 4th max salary for each dept having at least four employees. Maybe you should have a look at other analytic functions like rank() or dense_rank().
Hope that helps,
dhalek