private void btnThem_Click(object sender, EventArgs e)
        {
            clsUser user = new clsUser();
            user.User_name = txtTenNguoiDung.Text;
            user.Password = clsThamSoUtilities.CalculateMD5Hash(txtPwd.Text);
            if (user.Insert() == 1)
            {
                MessageBox.Show("Thêm thành công!");

            }
        }
 private void btnDangNhap_Click(object sender, EventArgs e)
 {
     string username = txtTenDN.Text;
     string passwd = txtPwd.Text;
     string hash =clsThamSoUtilities. CalculateMD5Hash(passwd);
     clsUser user = new clsUser();
     if (user.checkPasswd(username, hash)==true)
     {
         Utilities.clsThamSoUtilities.isSectionLogin = true;
         MessageBox.Show("Bạn đã đăng nhập thành công!");
         this.Close();
     }
 }
 public frmQuanTriNguoiDung()
 {
     InitializeComponent();
     clsUser user = new clsUser();
     gridUser.DataSource = user .GetAllData();
 }