I want my parameters in for the report to be populated dyanamically. i.e. when I select Country from first parameter drop-down list, the second parameter called City should be populated with only those cities in that country, and further, when I select city, my third parameter called center should get populated with only centers for that city.

How to do this in Crystal Reports 10?
PLease help out me, i need to do this badly.
Thanks and Regards
Amol Bhide