修改密码问题

修改密码如下:
    为什么有错呢,系统提示:  cmd.ExecuteNonQuery(); 已有打开的与此命令相关联的 DataReader，必须首先将它关闭。
 protected void Page_Load(object sender, EventArgs e)
    {
        string user = Request["user"].ToString();//用户名
        Label1 .Text= user ;
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        SqlConnection meteor = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["meteor"]);
        meteor.Open();
        SqlCommand comm = new SqlCommand("select * from studentlogin where username='" + Label1.Text + "' and password='" + this.TextBox1.Text + "'", meteor);

        SqlDataReader dr = comm.ExecuteReader();

        if (!dr.Read())
        {
            Response.Write("<script>alert('原密码错误！')</script>");
            dr.Close();
        }
        else
        {
            SqlCommand cmd = new SqlCommand("update studentlogin set password='" + TextBox2.Text + "'where username='" + Label1.Text + "'", meteor);
            cmd.ExecuteNonQuery();
            Response.Write("<script>alert(修改成功!'')</script>");
            meteor.Close();            
        }
    }