How to refresh datagrid in wpf application

Thanks.I tried it..but the selected row is not deleting from datagrid after performing the delete operations.Is there any solution for that..

This is my program...could you please help me to delete a selected row from grid after delete operation in this program...


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data.SqlClient;
using System.Data;

namespace WpfApplication1
{
///

/// Interaction logic for MainWindow.xaml
///

public partial class MainWindow : Window
{


public MainWindow()
{
InitializeComponent();
bindgrid();


}
private void bindgrid()
{

SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=book;User ID=sa;Password=nest123@!");
con.Open();
string cmd1 = "select * from book2";
SqlCommand cmd = new SqlCommand(cmd1, con);
SqlDataAdapter sda = new SqlDataAdapter(cmd);
cmd.ExecuteNonQuery();


DataTable dt = new DataTable("book2");

sda.Fill(dt);
dataGrid1.ItemsSource = dt.DefaultView;

}
//insert
private void button1_Click(object sender, RoutedEventArgs e)
{
DataTable dt=new DataTable();
SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=book;User ID=sa;Password=nest123@!");
con.Open();
try
{
object item=dataGrid1.SelectedItem;
string col1 = (dataGrid1.SelectedCells[0].Column.GetCellContent(item) as TextBlock).Text;
string col2 = (dataGrid1.SelectedCells[1].Column.GetCellContent(item) as TextBlock).Text;
string col3 = (dataGrid1.SelectedCells[2].Column.GetCellContent(item) as TextBlock).Text;
string col4 = (dataGrid1.SelectedCells[3].Column.GetCellContent(item) as TextBlock).Text;
string p = "insert into book2 values('" + col1 + "','"+col2+"','"+col3+"','"+col4+"')";
SqlCommand cmd = new SqlCommand(p, con);

cmd.ExecuteNonQuery();
}
catch (SqlException e1)
{
MessageBox.Show(e1.Message.ToString());
}
MessageBox.Show("value inserted");
dataGrid1.Items.Refresh();
con.Close();
}
//update
private void button2_Click(object sender, RoutedEventArgs e)
{
SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=book;User ID=sa;Password=nest123@!");

con.Open();
try
{


object item = dataGrid1.SelectedItem;
string bookid = (dataGrid1.SelectedCells[0].Column.GetCellContent(item) as TextBlock).Text;
string name = (dataGrid1.SelectedCells[1].Column.GetCellContent(item) as TextBlock).Text;
string author = (dataGrid1.SelectedCells[2].Column.GetCellContent(item) as TextBlock).Text;
string prize = (dataGrid1.SelectedCells[3].Column.GetCellContent(item) as TextBlock).Text;


SqlCommand cmd = new SqlCommand("update book2 set name=@name,author=@author,prize=@prize where bookid=@bookid", con);
cmd.Parameters.AddWithValue("@bookid", SqlDbType.NVarChar).Value = bookid;
cmd.Parameters.AddWithValue("@name", SqlDbType.NVarChar).Value = name;
cmd.Parameters.AddWithValue("@author", SqlDbType.NVarChar).Value = author;
cmd.Parameters.AddWithValue("@prize", SqlDbType.NVarChar).Value = prize;