Paging in GridView

In .aspx file :

<asp:GridView ID="GridView1" runat="server" PageSize="5" AllowPaging="true"         onpageindexchanging="GridView1_PageIndexChanging">
<PagerSettings Mode="Numeric" />
</asp:GridView>

In .aspx.cs file :

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

{

    protected void Page_Load(object sender, EventArgs e)

    {

        //sspi=Security Support Provider Interface ~= trusted connection

        if(!IsPostBack)

            DisplayEmployees();

    }

    private void DisplayEmployees()

    {

        string strcn = "data source=ADMIN-PC\\SQLEXPRESS;initial catalog=db17;integrated security=sspi";

        SqlConnection cn = new SqlConnection(strcn);

        SqlCommand cmd = new SqlCommand("select * from employees", cn);

        try

        {

            cn.Open();

            DataSet ds = new DataSet();

            SqlDataAdapter DA = new SqlDataAdapter(cmd);

            DA.Fill(ds);

            Session["ds"] = ds;

            GridView1.DataSource = ds;

            GridView1.DataBind();

        }

        catch (SqlException ex)

        {

        }

        finally

        {

            cn.Close();

        }

    }

    protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)

    {

        DataSet ds = (DataSet)Session["ds"];

        DataTable dt = ds.Tables[0];

        GridView1.DataSource = dt;

        GridView1.PageIndex = e.NewPageIndex;//this code must be written between Datasource and DataBind

        GridView1.DataBind();

    }

}

Table structure:

eid	fname	lname	age	salary	dept	doj
1	rajeev	sukla	23	12000	.net	23-Oct-11 12:00:00 AM
2	sowmya	kumari	23	19000	db	13-Nov-10 12:00:00 AM
3	kishore	kumar	27	36000	android	16-Oct-11 12:00:00 AM
4	abimanyu	biswal	22	null	android	20-Feb-10 12:00:00 AM
5	soni	kumar	24	21800	.net	21-Jun-09 12:00:00 AM
6	anu	_singh	22	12000	db	23-Oct-10 12:00:00 AM
7	_dinesh	moh%anty	23	15000	.net	26-Aug-09 12:00:00 AM
8	nishala	_kumari	22	18000	db	19-Jul-08 12:00:00 AM
1	rajeev	sukla	23	12000	.net	23-Oct-11 12:00:00 AM