How Update Data In Asp.Net GridView

<asp:GridView ID="GridView2" runat="server" AutoGenerateColumns="false" Width="100%" CssClass="gridview" DataKeyNames="Id" OnRowEditing="GridView2_RowEditing"
                    OnRowCancelingEdit="GridView2_OnRowCancelingEdit" OnRowUpdating="GridView2_OnRowUpdating" OnRowDeleting="GridView2_OnRowDeleting">
                    <Columns>
                      <%-- <asp:BoundField HeaderText="InvoiceNumber" DataField="InvoiceNumber" Visible="false" />--%>
                         <asp:BoundField HeaderText="Id" DataField="Id" Visible="true" />
                        <asp:BoundField HeaderText="Description" DataField="Description" />
                        <asp:BoundField HeaderText="TicketPrice" DataField="TicketPrice" />
                        <asp:BoundField HeaderText="Passengers" DataField="Passengers" />
                        <asp:BoundField HeaderText="IssuingFee" DataField="IssuingFee" />
                        <asp:BoundField HeaderText="TotalAmount" DataField="TotalAmount" />

                         <asp:CommandField HeaderText="Edit-Update" ShowEditButton="True" />
                         <asp:CommandField HeaderText="Delete" ShowDeleteButton="true" />
                    </Columns>
                </asp:GridView>

protected void GridView2_RowEditing(object sender, GridViewEditEventArgs e)
   {
       GridView2.EditIndex = e.NewEditIndex;
       GridView2.DataBind();
       gvbind();
   }
   protected void GridView2_OnRowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
   {
       GridView2.EditIndex = -1;
       gvbind();
   }
   protected void GridView2_OnRowUpdating(object sender, GridViewUpdateEventArgs e)
   {

       string s = ConfigurationManager.ConnectionStrings["conn"].ToString();
       p = new SqlConnection(s);
       SqlCommand cmd = new SqlCommand("Update_Item", p);
       cmd.CommandType = CommandType.StoredProcedure;
       cmd.Parameters.Add("@Id", SqlDbType.Int, 4).Value = Convert.ToInt32(GridView2.DataKeys[e.RowIndex].Value);

       cmd.Parameters.Add("@Description", SqlDbType.VarChar, 200).Value = ((TextBox)GridView2.Rows[e.RowIndex].Cells[1].Controls[0]).Text;
       cmd.Parameters.Add("@TicketPrice", SqlDbType.VarChar, 50).Value = ((TextBox)GridView2.Rows[e.RowIndex].Cells[2].Controls[0]).Text;
       cmd.Parameters.Add("@Passenger", SqlDbType.VarChar, 50).Value = ((TextBox)GridView2.Rows[e.RowIndex].Cells[3].Controls[0]).Text;
       cmd.Parameters.Add("@IsssuingFee", SqlDbType.VarChar, 50).Value = ((TextBox)GridView2.Rows[e.RowIndex].Cells[4].Controls[0]).Text;
       cmd.Parameters.Add("@TotalAmount", SqlDbType.VarChar, 50).Value = ((TextBox)GridView2.Rows[e.RowIndex].Cells[5].Controls[0]).Text;
       cmd.Connection.Open();
       cmd.ExecuteNonQuery();

       cmd.Connection.Close();
       GridView2.EditIndex = -1;

       gvbind();

   }
   protected void GridView2_OnRowDeleting(object sender, GridViewDeleteEventArgs e)
   {
       string s = ConfigurationManager.ConnectionStrings["conn"].ToString();
       p = new SqlConnection(s);
       SqlCommand cmd = new SqlCommand("Delete_Item", p);
       cmd.CommandType = CommandType.StoredProcedure;
       cmd.Parameters.Add("@Id", SqlDbType.Int, 4).Value = Convert.ToInt32(GridView2.DataKeys[e.RowIndex].Value);
       cmd.Connection.Open();
       cmd.ExecuteNonQuery();
       cmd.Connection.Close();
       gvbind();
   }

ALTER proc [dbo].[Update_Item]
(
@Id int,
@Description varchar(200),
@TicketPrice varchar(50),
@Passenger varchar(50),
@IsssuingFee varchar(50),
@TotalAmount varchar(50)

)as

update ItemMaster set Description=@Description, TicketPrice=@TicketPrice,Passengers=@Passenger,
                        IssuingFee=@IsssuingFee, TotalAmount=@TotalAmount
                       where Id=@Id