dataset读取xml

private void Button2_Click(object sender, System.EventArgs e)
  ...{
   DataSet ds=new DataSet();
   ds.ReadXml(Server.MapPath("people.xml"));
   this.DataGrid1.DataSource=ds;
   this.DataGrid1.DataBind();
  }

  private void Button1_Click(object sender, System.EventArgs e)
  ...{
  
   SqlConnection conn=new SqlConnection("server=.;uid=sa;pwd=123;database=pb");
   conn.Open();
   string sql="select * from layer";
   SqlDataAdapter da=new SqlDataAdapter(sql,conn);
      DataSet ds=new DataSet();
   da.Fill(ds,"aa");
   ds.WriteXml(Server.MapPath("mytest1.xml"));
   Response.Write("<script>alert('成功')</script>");

  }