public static List <KhachHangDTO> SelectKhachHangByTenKhachHang(String tenKhachHang) { return(!KhachHangDAO.CheckKhachHangByTenKhachHang(tenKhachHang) ? null : KhachHangDAO.SelectKhachHangByTenKhachHang(tenKhachHang)); }