APEX

I have an Interactive Report:

select ename "Employee Name",
mgr "Manager
from emp e, dept d
where e.deptno = d.deptno ;


That i'd like to have filtered by MGR when a Flash Pie Chart is clicked:

select null link,
mgr label,
count(emp_id) value
from emp e, dept d
where e.deptno = d.deptno
group by mgr ;

Can someone indicate how i'd do this?

Thanks in advance!
John