asp.net中怎样用DataGrid控件显示Sql Server数据库中的内容呢

using System;
using System.Collections;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Web;
using System.Web.SessionState;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.HtmlControls;

namespace WebApplication8
{
/// <summary>
/// WebForm2 的摘要说明。
/// </summary>
public class WebForm2 : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid DataGrid1;

private void Page_Load(object sender, System.EventArgs e)
{
//定义连接 这里以northwind为例
System.Data.SqlClient.SqlConnection con=new System.Data.SqlClient.SqlConnection("server=.;database=northwind;integrated security=sspi");
con.Open();
//声明新的Command对象
System.Data.SqlClient.SqlCommand cmd=new System.Data.SqlClient.SqlCommand("select * from employees",con);
//声明一个数据集
Sy