Edit and Update record in Grid View in asp.net

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

using System.Configuration;

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

{

    protected void Page_Load(object sender, EventArgs e)

    {

        if (IsPostBack == false)

        {

            data_bind();

        }

    }

    private void data_bind()

    {

        SqlDataAdapter adp = new SqlDataAdapter("select * from tbemp1", ConfigurationManager.ConnectionStrings["cn"].ConnectionString);

        DataSet ds = new DataSet();

        adp.Fill(ds);

        GridView1.DataSource = ds;

        GridView1.DataBind();

    }

    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)

    {

        GridView1.EditIndex = e.NewEditIndex;

        data_bind();

    }

    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)

    {

        Int32 empno,esl;

        String enam, eadd;

        enam = ((TextBox)(GridView1.Rows[e.RowIndex].FindControl("t1"))).Text;

        eadd = ((TextBox)(GridView1.Rows[e.RowIndex].FindControl("t2"))).Text;

        esl = Convert.ToInt32(((TextBox)(GridView1.Rows[e.RowIndex].FindControl("t3"))).Text);

        empno = Convert.ToInt32(((Label)(GridView1.Rows[e.RowIndex].FindControl("lk"))).Text);

        SqlConnection con = new SqlConnection();

        con.ConnectionString = ConfigurationManager.ConnectionStrings["cn"].ConnectionString;

        con.Open();

        SqlCommand cmd = new SqlCommand();

        cmd.CommandText = "Update tbemp1 set ename = @enam,eadd = @ed,esal = @esl where empno = @eno";

        cmd.Connection = con;

        cmd.Parameters.Add("@eno", SqlDbType.Int).Value = empno;

        cmd.Parameters.Add("@enam", SqlDbType.VarChar, 50).Value = enam;

        cmd.Parameters.Add("@ed", SqlDbType.VarChar, 50).Value = eadd;

        cmd.Parameters.Add("@esl", SqlDbType.Int).Value = esl;

        cmd.ExecuteNonQuery();

        cmd.Dispose();

        GridView1.EditIndex = -1;

        data_bind();

    }

   

}