public void Create(Product product,int quantity, int orderId)
        {
            OrderItem oitem = new OrderItem();

            oitem.OrderID = orderId;
            oitem.ProductName = product.ProductName;
            oitem.Quantity = quantity;
            oitem.Price = product.Price;
            oitem.Category = db.Categories.Find(product.CategoryID).CategoryName;
            oitem.Description = product.Description;
            db.OrderItems.Add(oitem);
            db.SaveChanges();
        }
 public void Edit(OrderItem orderitem)
 {
     db.Entry(orderitem).State = System.Data.Entity.EntityState.Modified;
     db.SaveChanges();
 }
 public void Delete(OrderItem orderitem)
 {
     db.OrderItems.Remove(orderitem);
     db.SaveChanges();
 }