C# LINQ在一对多中找到差异

// 定义订单类
public class Order
{
    public int OrderId { get; set; }
    public string OrderName { get; set; }
}

// 定义商品类
public class Product
{
    public int ProductId { get; set; }
    public string ProductName { get; set; }
    public int OrderId { get; set; }
}

// 创建订单集合
List<Order> orders = new List<Order>
{
    new Order { OrderId = 1, OrderName = "Order 1" },
    new Order { OrderId = 2, OrderName = "Order 2" },
    new Order { OrderId = 3, OrderName = "Order 3" }
};

// 创建商品集合
List<Product> products = new List<Product>
{
    new Product { ProductId = 1, ProductName = "Product 1", OrderId = 1 },
    new Product { ProductId = 2, ProductName = "Product 2", OrderId = 1 },
    new Product { ProductId = 3, ProductName = "Product 3", OrderId = 2 }
};

// 使用LINQ查询找到差异
var diffProducts = products.Where(p => !orders.Any(o => o.OrderId == p.OrderId));

// 输出差异商品
foreach (var product in diffProducts)
{
    Console.WriteLine($"Product {product.ProductId} ({product.ProductName}) is not associated with any order.");
}