subreport executing multiple times based on parameter values

i created a subreport that runs off a query with from three different parameters (which are dropdowns). Based on the first parameter, second parameter gets populated. Based on the second, third parameter, and based on the third parameter, subreport gets populated. Here is the issue. if the third parameter has 10 values in the drop down, subreport is executed 10 times. I also figured out that when the second parameter is chosen, subreport is executed 10 times with empty values. So i'll have to restrict the subreport from getting executed only once.