Hi friends, I have two cascading LOVs. After changing value of my first LOV in second LOV appropriate values are populated.

First LOV:
name - P2_DEPTNO
select dname,
deptno
from dept
order by 1;
Second LOV:
name - P2_EMPNO
select ename,
empno
from emp
where deptno = :P2_DEPTNO;
cascading LOV parent - P2_DEPTNO
What should I add to set default value of second LOV (first row from query) after changing first LOV value?
Thanks a lot in advance