Linq 12 ABM

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _12 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        RellenarGridView();
    }

    protected void RellenarGridView()
    {
        DataClassesDataContext db = new DataClassesDataContext();

        var qry = from ship in db.Shippers
                  select ship;

        GridView1.DataSource = qry;
        GridView1.DataBind();
    }

    protected void Actualizar(int id)
    {
        DataClassesDataContext db = new DataClassesDataContext();
        var qry = (from ship in db.Shippers
                  where ship.ShipperID == id
                  select ship).Single();

        qry.CompanyName = txtBxCompanyName.Text;
        qry.Phone = txtBxPhone.Text;

        db.SubmitChanges();

    }

    protected void Insertar()
    {
        DataClassesDataContext db = new DataClassesDataContext();

        Shippers ship = new Shippers();

        ship.CompanyName = txtBxCompanyName.Text;
        ship.Phone = txtBxPhone.Text;

        db.Shippers.InsertOnSubmit(ship);
        db.SubmitChanges();


    }

    protected void Eliminar(int id)
    {
        DataClassesDataContext db = new DataClassesDataContext();
        var qry = (from ship in db.Shippers
                   where ship.ShipperID == id
                   select ship).Single();

        db.Shippers.DeleteOnSubmit(qry);
        db.SubmitChanges();

    }

    protected void Button1_Click1(object sender, EventArgs e)
    {
        Actualizar(Convert.ToInt32(txtId.Text));
        RellenarGridView();
    }
    protected void Button2_Click(object sender, EventArgs e)
    {
        Insertar();
        RellenarGridView();
    }
    protected void Button3_Click(object sender, EventArgs e)
    {
        Eliminar(Convert.ToInt32(txtId.Text));
        RellenarGridView();
    }


}