如何使用实体框架将相同的Pizza添加到订单表中

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

// 创建实体类
public class Pizza
{
    public int Id { get; set; }
    public string Type { get; set; }
    public string Size { get; set; }
    // 其他属性...
}

public class Order
{
    public int Id { get; set; }
    public string CustomerName { get; set; }
    public DateTime OrderTime { get; set; }
    public List<Pizza> Pizzas { get; set; }
    // 其他属性...
}

// 创建上下文类
public class PizzaContext : DbContext
{
    public DbSet<Pizza> Pizzas { get; set; }
    public DbSet<Order> Orders { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer("连接字符串"); // 替换为实际的数据库连接字符串
    }
}

// 在订单表中添加相同的Pizza
public void AddPizzaToOrder()
{
    using (var context = new PizzaContext())
    {
        // 获取要添加的Pizza
        var pizzaToAdd = context.Pizzas.FirstOrDefault(p => p.Type == "Cheese" && p.Size == "Large");

        // 创建新的订单
        var order = new Order
        {
            CustomerName = "John Doe",
            OrderTime = DateTime.Now,
            Pizzas = new List<Pizza>()
        };

        // 添加相同的Pizza到订单中
        order.Pizzas.Add(pizzaToAdd);

        // 保存更改
        context.Orders.Add(order);
        context.SaveChanges();
    }
}