Dynamic combo box filter

Question

Hi.i have three combo boxes that require dynamic filtration depending on what a user selects on the 1st and the 2nd combo boxes.The first one has divisions,second one has locations and the 3rd one has sublocations.they are all in a datalist n depending on wat the user selects,it filters the second n the second filters the third.anyone who has an idea on how to approach this in asp.net.