DataSet綁定Hashtable為DropDownList提供數據源

把某些固定的數據源綁定寫到類的方法裡，能夠使代碼更好的適應變化。下面的方法並沒有放到類裡只是簡單的做了示范：   

  protected void Page_Load(object sender, EventArgs e)
    {
        string connectionString = ConfigurationManager.ConnectionStrings["tahx2006ConnectionString"].ConnectionString;
        string tableName = "SYS_DIC_BalancePeriod";
        string key = "SDBP_MID";
        string value = "SDBP_MCOSTNO";

        Hashtable ht = GetHashtable(connectionString,tableName, key, value);
        DropDownList1.DataSource = ht;
        DropDownList1.DataTextFIEld = "value";
        DropDownList1.DataValueFIEld = "key";
        DropDownList1.DataBind();
    }

        /// <summary>
        /// 提供Hashtable用來綁定DropDownList
        /// </summary>
        /// <param name="connectionString">鏈接數據庫的字符串</param>
        /// <param name="tableName">要鏈接的表名</param>
        /// <param name="key">用來做HashTable鍵的列名</param>
        /// <param name="value">用來做HashTable值的列名</param>
        public Hashtable  GetHashtable(string connectionString,string tableName, string key,string value )
        {
            string sqlString = "select " + key + "," + value + " from " + tableName;
            SqlConnection con = new SqlConnection(connectionString);