Row updating event in gridview ASP.NET

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using MySql.Data.MySqlClient;
using System.IO;


public partial class _Default : System.Web.UI.Page
{
    MySqlConnection con = new MySqlConnection("user id=root; password=admin; database=qms; server=localhost");

   protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
            bind();
    }
   public void bind()
   {

       con.Open();
       string q = "select * from exam";
       MySqlDataAdapter da = new MySqlDataAdapter(q, con);
       DataSet ds = new DataSet();
       da.Fill(ds, "emp");
       GridView1.DataSource = ds;
       GridView1.DataBind();
       //con.Close();
   }

    protected void Button1_Click(object sender, EventArgs e)
    {
       bind();
    }

    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        bind();
    }

    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        bind();
    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
        int id = Int32.Parse(GridView1.DataKeys[e.RowIndex].Value.ToString());
        TextBox tname = (TextBox)row.FindControl("nam");
        TextBox tques = (TextBox)row.FindControl("que");
        MySqlCommand cmd = new MySqlCommand("update exam set name1=@name,ques=@ques where id = @id", con);
        cmd.Parameters.Add("@id", MySqlDbType.Int16).Value = id;
        cmd.Parameters.Add("@name", MySqlDbType.VarChar, 30).Value = tname.Text.Trim();
        cmd.Parameters.Add("@ques", MySqlDbType.VarChar,40).Value = tques.Text.Trim();
        con.Open();
        cmd.ExecuteNonQuery();
        GridView1.EditIndex = -1;
        bind();
    }