public bool create(Bill_Online_Detail bill_Online_Detail)
 {
     try
     {
         bill_Online_Detail.created_at = DateTime.Now;
         bill_Online_Detail.updated_at = DateTime.Now;
         db.Bill_Online_Detail.Add(bill_Online_Detail);
         db.SaveChanges();
         return(true);
     }
     catch (Exception e)
     {
         return(false);
     }
 }
 public bool update(Bill_Online_Detail billdetail, int id_bill, int id_food)
 {
     try
     {
         billdetail.updated_at = DateTime.Now;
         (from billdt in db.Bill_Online_Detail
          where billdt.id_bill == id_bill && billdt.id_drink == id_food
          select billdt)
         .ToList()
         .ForEach((p) =>
         {
             p.quantity = billdetail.quantity;
             p.price    = billdetail.price;
         });
         db.SaveChanges();
         return(true);
     }
     catch (Exception e)
     {
         return(false);
     }
 }