Grid view Edit using check boxes

 set the property DataKeyNames ="id" for gridview  and use above java script for selecting all check boxes at a time

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;
using System.Text;

public partial class _Default : System.Web.UI.Page
{

    MySqlConnection con = new MySqlConnection("data source=localhost;database=test;user id=root;password=root");

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {

            MySqlDataAdapter da = new MySqlDataAdapter("select * from student", con);
            DataSet ds = new DataSet();

            da.Fill(ds, "st");
            gvdevice.DataSource = ds;
            gvdevice.DataBind();

        }



    }


    protected void Button1_Click(object sender, EventArgs e)
    {

        StringBuilder IDs = new StringBuilder();
        int count = gvdevice.Rows.Count;

        for (int i = 0; i < count; i++)
        {
            CheckBox chkSelect = gvdevice.Rows[i].FindControl("chkSelect") as CheckBox;
            if (chkSelect.Checked)
            {
               object id=gvdevice.DataKeys[i].Value;
               int idr = int.Parse(id.ToString());

               string abcd = "abcd";
               string s = "update student set name='" + abcd + "' where id='" + idr + "'";
                MySqlCommand cmd=new MySqlCommand(s,con);
                con.Open();
                cmd.ExecuteNonQuery();
                con.Close();

            }
        }
    }
}