RadioButton如何和dropdownlist 动态绑定？

if (!IsPostBack)
{
SqlConnection con = new SqlConnection("server=.;uid=sa;pwd=sa;database=db");
SqlDataAdapter ada = new SqlDataAdapter("select * from ProvinceInfo", con);
DataTable dt = new DataTable();
ada.Fill(dt);
ddlAddress1.DataSource = dt;
ddlAddress1.DataTextField = "Province";
ddlAddress1.DataValueField = "ProvinceId";
ddlAddress1.DataBind();
string aa = this.ddlAddress1.SelectedValue.ToString();
SqlDataAdapter adas = new SqlDataAdapter("select * from CityInfo where ProvinceInfoNo=" + aa, con);
DataTable dts = new DataTable();
adas.Fill(dts);
this.ddlAddress2.DataSource = dts;
ddlAddress2.DataTextField = "City";
ddlAddress2.DataValueField = "CityI