public List <ChiTietHoaDonDaiLy> getHoaDonDaiLyTheoThang(int startMonth, int startYear, int endMonth, int endYear)
{
DateTime startDate = new DateTime(startYear, startMonth, 1);
DateTime endDate = new DateTime(endYear, endMonth, 1);
endDate = endDate.AddMonths(1).AddDays(-1);
return(HoaDonDaiLy.Where(ct =>
ct.HoaDon.NgayLap >= startDate &&
ct.HoaDon.NgayLap <= endDate).ToList());
}
