public void ThemKH(string HoTen, string DiaChi, DateTime NgaySinh, string Email, string SDT)
{
KhachHang Kh = new KhachHang();
Kh.HoTen = HoTen;
Kh.NgaySinh = NgaySinh;
Kh.SDT = SDT;
Kh.Email = Email;
Kh.DiaChi = DiaChi;
da.ThemTTKH(Kh);
}