如何使用Entity Framework和.NET 5.0构造查询来查找关联表中不匹配的实体？

using System;
using System.Linq;
using Microsoft.EntityFrameworkCore;

// 定义实体类
public class Order
{
    public int OrderId { get; set; }
    public string OrderNumber { get; set; }
    public int CustomerId { get; set; }
    public Customer Customer { get; set; }
}

public class Customer
{
    public int CustomerId { get; set; }
    public string CustomerName { get; set; }
    public ICollection<Order> Orders { get; set; }
}

// 定义数据库上下文类
public class MyDbContext : DbContext
{
    public DbSet<Order> Orders { get; set; }
    public DbSet<Customer> Customers { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("连接字符串");
    }
}

// 查询关联表中不匹配的实体
public static void FindMismatchedEntities()
{
    using (var context = new MyDbContext())
    {
        var mismatchedOrders = context.Orders
            .Include(o => o.Customer)
            .Where(o => o.Customer == null)
            .ToList();

        foreach (var order in mismatchedOrders)
        {
            Console.WriteLine($"订单号：{order.OrderNumber}，找不到对应的客户。");
        }
    }
}

// 调用方法进行查询
FindMismatchedEntities();