Stings Size Limitation

Hello All

I got a problem  with an IN clause query  with too many literals  or String concatination

ex:

  1  select listagg(rn,',') within group (order by 1)
  2  from (
  3  select rownum rn  from dual connect by level < 2000
  4* )
SQL> /
select rownum rn  from dual connect by level < 2000
                       *
ERROR at line 3:
ORA-01489: result of string concatenation is too long

(or)

declare
l_empno varchar2(4000 char);

begin

select listagg(rn,',') within group (order by 1) into l_empno
from (
select rownum rn  from dual connect by level < 2000);

l_empno := l_empno||','||l_empno;

select * into l_empno from emp where empno in l_empno;