public void Delete(T entity)
        {
            using (ShoppingMallEntities context = new ShoppingMallEntities())
            {
                context.Entry(entity).State = EntityState.Deleted;

                context.SaveChanges();
            }
        }
        public void Insert(T entity)
        {
            using (ShoppingMallEntities context = new ShoppingMallEntities())
            {
                context.Set <T>().Add(entity);

                context.SaveChanges();
            }
        }