select min(salary) from salary where salary in(select top 3
salary from salary order by salary desc)

select top 2(salary) from (select top 3 (salary) from
dbo.employee order by salary desc) 
order by salary

select sal,rownum from (select sal from emp
 order by sal desc)
where rownum<=3
MINUS
 select sal,rownum from (select sal from emp
 order by sal desc)
where rownum<=1

select max(sal) from emp e1 where 1< (select count(distinct sal) from emp e2 where e1.sal <= e2.sal)

To make it generic if u want N'th highest salary;

select max(sal) from emp e1 where (N-1)< (select count(distinct sal) from emp e2 where e1.sal <= e2.sal)

And to get the N'th min sal :

select min(sal) from emp e1 where (N-1)< (select count(distinct sal) from emp e2 where e1.sal >= e2.sal)