Paging in Gridview using C#

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="Pid"
    AllowPaging="true" AllowSorting="True" BorderColor="Black" BorderStyle="Solid"
GridLines="None" ShowFooter="True"  OnPageIndexChanging="GridView1_PageIndexChanging"
CaptionAlign="Top" Width="118%" >

<Columns>
    <asp:BoundField HeaderStyle-Height="29px" HeaderText="PID" DataField="PID"
        Visible="false">
        <HeaderStyle Height="29px"></HeaderStyle>
    </asp:BoundField>
    <asp:BoundField HeaderText="Postcode" DataField="Postcode" />
    <asp:BoundField HeaderText="Latitude" DataField="Latitude" />
    <asp:BoundField HeaderText="Longitude" DataField="Longitude" />
    <asp:BoundField HeaderText="Easting" DataField="Easting" />
</Columns>
</asp:GridView>


Please find the code for Aspx.cs file

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                BindData();
            }
        }protected void BindData()
  {
      DataSet dsImage = new DataSet();
      SqlConnection con = new SqlConnection("Data Source=Chandu/SQLExpress;Initial 
      Catalog=Test;Persist Security Info=True;User ID=sa;Password=sa;Connect Timeout=800");
      con.Open();
      SqlCommand cmd = new SqlCommand();
      cmd.Connection = con;
      cmd.CommandType = CommandType.Text;
      cmd.CommandText = "Select top 1000 [PID],[Postcode],[Latitude],[Longitude],[Easting] FROM [Test].[dbo].[PostalCodes]";
       SqlDataAdapter da = new SqlDataAdapter(cmd);
       da.Fill(dsImage);
            try
            {

                if (dsImage.Tables.Count > 0)
                {
                    if (dsImage.Tables[0].Rows.Count > 0)
                    {
                        GridView1.DataSource = dsImage.Tables[0];
                        GridView1.DataBind();
                        con.Close();
                    }
                }
            }
            catch (Exception ex)
            {

            }
        }

 protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e){
             GridView1.PageIndex = e.NewPageIndex;
             BindData();
 }