/// <summary>
        /// 根据传入的语句，得到DataSet
        /// </summary>
        /// <param name="strsql"></param>
        /// <returns></returns>
        public DataSet GetDataSet(string strsql)
        {
            //this.Reset();

            cmd = new SqlCommand("", conn);
            cmd.CommandText = strsql;
            DataSet ds = new DataSet();
            da = new SqlDataAdapter();
            da.SelectCommand = cmd;
            da.Fill(ds);
            return ds;
        }

        /// <summary>
        /// 根据传入的语句，得到DataTable
        /// </summary>
        /// <param name="strsql"></param>
        /// <returns></returns>
        public DataTable GetDataTable(string strsql)
        {
            DataSet ds = GetDataSet(strsql);
            return ds.Tables[0];
        }

------解决方案--------------------
C# code

public Dictionary<string, A> GetDDL()
{
Dictionary<string, A> d = new Dictionary<string, A>();  
            d.Add("aa", new A("1", "xx"));  
            d.Add("bb", new A("2", "yy"));  
            d.Add("cc", new A("3", "zz"));  
            return d;
   
} 
            //DataList1.DataSource = d;  
            //DataList1.DataBind(); 
            //绑定。

------解决方案--------------------
调用：

DropDownListData(this.DropDownList2,参数，参数）



把下面的代码写入一个公共类       
public static void DropDownListData(System.Web.UI.WebControls.DropDownList dd,string kindno,string dept)
       {
           dd.DataSource = DAL.DBAccess.Qery(select * from 表)//在这里绑定dataset
           dd.DataTextField = "kind_name";
           dd.DataValueField = "kind_no";
           dd.DataBind();
       }
       /// <summary>
       /// 执行查询语句，返回DataSet
       /// </summary>
       /// <param name="SQLString">查询语句</param>
       /// <returns>DataSet</returns>
       public static DataSet Query(string SQLString, params SqlParameter[] cmdParms)
       {
           using (SqlConnection connection = new SqlConnection(connStr))
           {
               SqlCommand cmd = new SqlCommand();
               PrepareCommand(cmd, connection, null, SQLString, cmdParms);
               using (SqlDataAdapter da = new SqlDataAdapter(cmd))
               {
                   DataSet ds = new DataSet();
                   try
                   {
                       da.Fill(ds, "ds");
                       cmd.Parameters.Clear();
                   }
                   catch (System.Data.SqlClient.SqlException ex)
                   {
                       throw new Exception(ex.Message);
                   }
                   finally
                   {
                       connection.Dispose();
                       connection.Close();
                   }
                   return ds;
               }
           }
       }