APEX

Hello

I have two checkboxes on a Interactive Report:

My query is as follows:

select
apex_item.checkbox(1, empno, 'ENABLED'),
apex_item.checkbox(2, deptno, 'ENABLED'),
ename,
sal
from emp;

I have a conditional button 'Check N Update' which will invoke the Pl/SQL process:

FOR i in 1..APEX_APPLICATION.G_F01.count
LOOP
l_empno := APEX_APPLICATION.G_F01(i);

UPDATE XXX ....;

END LOOP;

FOR i in 1..APEX_APPLICATION.G_F02.count
LOOP
l_empno := APEX_APPLICATION.G_F02(i);

UPDATE XXX ....;

END LOOP;

What I need is I need to check a CONDITION, if BOTH the checkbox's are selected then I need to throw an ERROR saying.
YOU CANNOT SELECT BOTH the boxes.

Please let me know how can I get this.

Appreciate your help.

thanks