One DropDownList dependent on other DropDownList ASP.Net

Hi  every one

I have 3 drop down list in my page that fill data from Data base

first DDL show city name 

second DDL show region

third DDL show shopping center

I want when user click DDL1 and select city in DDL2 just show region of that city and when user select region in DDL 3 just show shopping center of that region.

and this is my Table in DATABASE

how i can do it?

thanks