Populate Dropdown list based on another dropdown list [duplicate]

Answer 1

you can populate second drp (DropDownList) by this ways: Connect 1st drp with table, which calls this query: (in SQLDataSource1)

SELECT [id], [name] FROM Products

in 2nd drp you should call (in SQLDataSource2)

 SELECT [id], [name] FROM Models WHERE ProductID=@Product_id

in SQLDataSource2 select command Property add Parameter value for Product_id it must be drp1.SelectedValue

Note: Don't forget Enable AutoPostBack for drp1