In asp.net how to short data in a gridview using Linq

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{

public static int a = 2;

protected void Page_Load(object sender, EventArgs e)

{

if (!IsPostBack)
{

DataClassesDataContext db = new DataClassesDataContext();

IQueryable student = from s in db.StudentInformations

select s;

GridView1.DataSource = student;

GridView1.DataBind();

}

}

protected void GridView1_Sorting(object sender, GridViewSortEventArgs e)
{
if (a % 2 == 0)
{
DataClassesDataContext db = new DataClassesDataContext();
IQueryable studentInformation = (from s in db.StudentInformations
select s).OrderByDescending(s => s.Student_ID);
GridView1.DataSource = studentInformation;
GridView1.DataBind();
e.Cancel = true;
a++;

}
else
{
DataClassesDataContext db = new DataClassesDataContext();
IQueryable studentInformation = (from s in db.StudentInformations
select s);
GridView1.DataSource = studentInformation;
GridView1.DataBind();
e.Cancel = true;
a++;
}
}
}