How to bind three tables to the Treeview?

Question

I have 3 tables in my database having foreign keys to child tables.

->Parent(Table1)

             ->child1(Table2)

                           ->subchild1(Table3)

                           ->subchild2 (Table3)

 

             ->child2 (Table2) 

                             ->subchild3(Table3)

                             ->subchild4 (Table3)

How to bind these 3 tables to Tree View?

And finally This Tree view should be inside the Dropdown List. When I click on the dropdown list,The above format should display.

             Thanks in Advance........