public class Area
{
 //建議編寫“實體類”的時候一定要用屬性，不要用字段
 //因為有些控件數(shù)據(jù)綁定的時候只認屬性，不認字段（大多數(shù)都是）
 public int AreaId
 {
  get;
  set;
 }
 public string AreaName
 {
  get;
  set;
 }
 //public int AreaId;
 //public string AreaName;
 public override string ToString()
 {
  return AreaName;
 }
}

private void LoadProvince()
{
 List<Area> list = new List<Area>();
 #region 初始化List集合
 string constr = ConfigurationManager.ConnectionStrings["sql"].ConnectionString;
 using (SqlConnection con = new SqlConnection(constr))
 {
  string sql = "select * from TblArea where AreaPid=0";
  using (SqlCommand cmd = new SqlCommand(sql, con))
  {
   con.Open();
   using (SqlDataReader reader = cmd.ExecuteReader())
   {
    if (reader.HasRows)
    {
     while (reader.Read())
     {
      //reader的索引是根據(jù)實際查詢出來的的列的索引來計算的而不是實際表中的索引，除非查詢語句使用select *.
      Area model = new Area() { AreaId = reader.GetInt32(0), AreaName = reader.GetString(1) };
      list.Add(model);
     }
    }
   }
  }
 }
 #endregion
 cboProvince.DisplayMember = "AreaName";
 cboProvince.ValueMember = "AreaId";
 cboProvince.DataSource = list;
}