Declare @position Char(33)
Set @position = 'sales'
Select ename, job From
(
	Select *, ROW_NUMBER() Over (Partition By job Order By Sal) As rn From Ex 
) As a
Where job = @position AND rn = 3

select max(salary)
from (
      select '20' as salary
      union all select '100'
   ) t

----
20

(1 row(s) affected)

create table #emp(ename varchar(34),job char(33),sal varchar(22))
insert into #emp values('sa','sales','400')
insert into #emp values('ka','manager','4000')
insert into #emp values('sam','Markting','2500')
insert into #emp values('sabu','system','3900')

SELECT TOP 3 *
FROM #emp
ORDER BY CAST(sal AS INT) DESC

DROP TABLE #emp