how do we fetch the data from database and show in listbox

DataTable dt = ConnectionClass.ReturnTable("select * from tbl_Product ORDER BY ProductID");//obj.ReturnTable("select * from tbl_Sparte");
        DataRow dr = dt.NewRow();
        dr["Product"] = "..SELECT..";
        dr["ProductID"] = "0";       
        dt.Rows.InsertAt(dr, 0);
        ddlProduct.DataSource = dt;
        ddlProduct.DataTextField = "Product";
        ddlProduct.DataValueField = "ProductID";
        ddlProducte.DataBind();