Check Only One Item In A Check Box

trigger when checkbox changed

declare
  l_current_record number;
  l_last_record    number;
begin
  l_current_record := :system.trigger_record;

  last_record;
  l_last_record := :system.cursor_record;
  
  first_record;
    
  for i in 1 .. l_last_record loop
    if :system.cursor_record <> l_current_record then
       :SM_ACT_FLAG := 0;
    end if;
    next_record;
  end loop;
  
  go_record(l_current_record);
end;