how can insert bulk data from gridview to database

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="Insert_data_from_Gridview_database._Default" %>





   


   

   

   
   
   
            Text="Insert Records" />
            style="height: 26px" Text="Show Records" />
   

   

using System;
using System.Collections;
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 System.Data.SqlClient;
namespace Insert_data_from_Gridview_database
{
    public partial class _Default : System.Web.UI.Page
    {
        string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlCommand com;

        protected void btn_show_Click(object sender, EventArgs e)
        {
            DataSet reportData = new DataSet();
            reportData.ReadXml(Server.MapPath("student.xml"));
            GridView1.DataSource = reportData;
            GridView1.DataBind();
        }

        protected void btn_insert_Click(object sender, EventArgs e)
        {
            foreach (GridViewRow g1 in GridView1.Rows)
            {
                SqlConnection con = new SqlConnection(connStr);
                com = new SqlCommand("insert into student(sid,sname,smarks,saddress) values ('" + g1.Cells[0].Text + "','" + g1.Cells[1].Text + "','" + g1.Cells[2].Text + "','" + g1.Cells[3].Text + "')", con);
                con.Open();
                com.ExecuteNonQuery();
                con.Close();

            }
            Label1.Text = "Records inserted successfully";
        }
    }
}