How to edit dynamic gridview rows

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
            onrowdatabound="GridView1_RowDataBound1">
            <Columns>
                <asp:BoundField DataField="CODE" HeaderText="CODE" />
                <asp:BoundField DataField="REFCODE" HeaderText="REFCODE" />
            <asp:TemplateField>
            <ItemTemplate>
             <asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="True"
                    onselectedindexchanged="DropDownList1_SelectedIndexChanged" Width="200px">
                </asp:DropDownList>
            </ItemTemplate>
            </asp:TemplateField>
                 </Columns>
</asp:GridView>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using System.Configuration;

public partial class Default3 : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection("--------------------------------");
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            con.Open();
            SqlCommand cmd = new SqlCommand(" write your query", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            con.Close();
            GridView1.DataSource = ds;
            GridView1.DataBind();
        }
    }
    protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
    protected void GridView1_RowDataBound1(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            con.Open();
            var ddl = (DropDownList)e.Row.FindControl("DropDownList1");
            int CountryId = Convert.ToInt32(e.Row.Cells[0].Text);
            SqlCommand cmd = new SqlCommand(" write your query ", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds);
            ddl.DataSource = ds;
            ddl.DataTextField = "xxxxx";
            ddl.DataValueField = "xxxxx";
            ddl.DataBind();
            con.Close();
        }
    }
}