get specific data from other database tables

Question

Hi!
   i have three tables in database province,division, and subdivision. i entered 4 provinces in province table using asp.net web page1. in next web page2 i used dropdown which get data from province table. for each province in dropdown i entered 6 divisions using textbox and save it in the division table. now in third web page3 i used two dropdowns one for province and one for division and a text box for subdivision entry.
i want that when i select a province from dropdown(e.g punjab) so the dropdown2 show me those divisions that i have entered for that particular province(e.g divsion1,divsion2 for punjab),not all the divisions of all the provinces. how is it possible?????please help me