Dear all,

There are three dropdownlist in a form in PHP.

country  dropdownlist

state dropdownlist

city dropdownlist
In MySql database there are three tables  table_country, table_state, table_city. 

When I select country dropdownlist all related state will be shown in state dropdownlist and when I select state dropdownlist all related city will be shown in city dropdownlist.
Please help me how to do ?