求c#省市二级联动代码

求c#省市二级联动代码，最好有图文解释的，可以的话做成WORD，发到我QQ邮箱里，我数据库是SQL2000，我做了两个子表了，一个是省，一个是市

下面的就是简单的查询

这是业务逻辑层的代码
 /// <summary>
    /// 获得所有省份 
    /// </summary>
    /// <returns>返回DataSet类型</returns>
    public DataSet GetProvinceInfo()
    {
    String SQL_SelectPro = "select * from ProvinceDict";
    return SQLHelper.SqlHelper.ExecuteDataset(Config.DbConnectionStore.TheInstance.GetConnectionStringUser(), CommandType.Text, SQL_SelectPro);

    }
  /// <summary>
    /// 根据省份id返回城市信息
    /// </summary>
    /// <param name="cityID">cityID</param>
    /// <returns>返回DataSet类型</returns>
    public DataSet GetProvinceInfoByCityID(int ProvinceID)
    {
    String SQL_SelectCity = "select * from CityDict where ProvinceID='" + ProvinceID + "'";
    return SQLHelper.SqlHelper.ExecuteDataset(Config.DbConnectionStore.TheInstance.GetConnectionStringUser(), CommandType.Text, SQL_SelectCity);（这是DAl里面的方法）

    }

这是表示层代码（用dropdownlist）

 /// <summary>
    /// 加载省信息
    /// </summary>
    private void JzProvince()
    {
    this.ddlprovince.DataSource = new BLL.NewInfo.TerminalOperator().GetProvinceInfo();
    this.ddlprovince.DataTextField = "ProvinceName";
    this.ddlprovince.DataValueField = "ProvinceID";
    this.ddlprovince.DataBind();
    }
    /// <summary>
    /// 根据省初始化市
    /// </summary>
    private void InitCityByProvince()
    {

    ddlcity.Items.Clear();
    String pid = ddlprovince.SelectedValue;
    DataSet ds = BLL.NewInfo.TerminalOperator.TheInstance.GetProvinceInfoByCityID(Int32.Parse(pid));
    if (ds.Tables[0].Rows.Count > 0)
    {
    this.ddlcity.DataSource = ds;
    this.ddlcity.DataTextField = "CityName";
    this.ddlcity.DataValueField = "CityID";
    this.ddlcity.DataBind();
    }

}