about mysql connection with .net

protected void Page_Load(object sender, EventArgs e)
  {
      try
      {
          if (!IsPostBack)
          {
              Classmysql.getconn();
              txtid.Focus();
              txtname.Text = "neha";
              str = "select max(sno+1) from tblid";
              cmd = new MySqlCommand(str, Classmysql.con);
              dtp = new MySqlDataAdapter(cmd);
              ds = new DataSet();
              dtp.Fill(ds);
              if (ds.Tables[0].Rows[0][0] == DBNull.Value)
              {
                  txtid.Text = "1";
              }
              else
              {
                  txtid.Text = ds.Tables[0].Rows[0][0].ToString();
              }

              cmd = new MySqlCommand("insert into tblid values(" + txtid.Text + ",'" + txtname.Text + "','1')", Classmysql.con);
              tn = Classmysql.con.BeginTransaction(IsolationLevel.Serializable);
              cmd.Transaction = tn;
              cmd.ExecuteNonQuery();
              tn.Commit();

              str = "select * from tblid";
              cmd = new MySqlCommand(str, Classmysql.con);
              dtp = new MySqlDataAdapter(cmd);
              ds = new DataSet();
              dtp.Fill(ds);
              GridView1.DataSource = ds;
              GridView1.DataBind();
              Classmysql.closeconn();
                     }
      }
      catch (MySqlException ee)
      {
          //  tn.Rollback();
          excepionmethod();
      }

  }