我的第二个C#代码

我写的第二个C#
  protected void Page_Load(object sender, EventArgs e)
    {

        {

           string strConnection = System.Configuration.ConfigurationManager.AppSettings["connString"];
           // string strConnection = System.Configuration.ConfigurationSettings.AppSettings["connString"];


            //DataSet
            SqlConnection Conn;
            SqlDataAdapter Adqt;
            DataSet Ds;
            string strSql="select * from table_1";

            Conn = new SqlConnection(strConnection);
            Conn.Open();
          
            Ds = new DataSet();
            Adqt = new SqlDataAdapter(strSql, Conn);
            Adqt.Fill(Ds, "table_1");
            GridView1.DataSource = Ds.Tables["table_1"].DefaultView;
            GridView1.DataBind();
            Ds.Clear();       
            Conn.Close();


            //DataReader
            SqlCommand Cmd;
            SqlDataReader Rd;

            Conn = new SqlConnection(strConnection);
            Conn.Open();
            Cmd = new SqlCommand(strSql, Conn);

            Rd = Cmd.ExecuteReader();
            int i=0;
            while (Rd.Read())
            {
                i++; 
                //i = i + 1
                Response.Write(i);
                Response.Write( " " + Rd["aaa"].ToString);
                //为什么不能这样 Response.Write( i.ToString + Rd["aaa"].ToString);
            }
            Rd.Close();
            Conn.Close();

        }
    }