How to optimize this??

Question

hello,
i wrote this for extracting 9th highest salary from emp table.
SQL> select min(sal) from
2 (select distinct sal from emp
3 where sal is not null
4 order by sal desc)
5 where rownum<=9;
MIN(SAL)
1250
But It has limitation. when we enter rownum more than existing rows then it gives minimum sal which is at the last position. rather than giving error or any different sense.
following is the query which has not satisfied its use in proper.
SQL> select min(sal) from
2 (select distinct sal from emp
3 where sal is not null
4 order by sal desc)
5 where rownum<=40
6 /
MIN(SAL)
800
where 800 is on last positon in 14 rows table.
please optimize and solve my problem.

Answer 1

user8710598 wrote:
only optimize or edit posted query...i knw the rank is given correct ans.That's a little demanding and rude of you. People are trying to help by understanding what you are actually trying to achieve.
Anyway...
SQL> ed
Wrote file afiedt.buf
  1  select sal
  2  from (
  3    select sal, rownum as rn
  4    from (
  5      select distinct sal
  6      from emp
  7      order by sal desc
  8      )
  9    )
10* where rn = 9
SQL> /
       SAL
      1250
SQL> ed
Wrote file afiedt.buf
  1  select sal
  2  from (
  3    select sal, rownum as rn
  4    from (
  5      select distinct sal
  6      from emp
  7      order by sal desc
  8      )
  9    )
10* where rn = 40
SQL> /
no rows selected
SQL>