如何使用Entity Framework在连接表上实现Where

// 连接表实体类
public class OrderItem
{
    public int Id { get; set; }
    public int OrderId { get; set; }
    public int ProductId { get; set; }
    public int Quantity { get; set; }
}

// 上下文类
public class MyDbContext : DbContext
{
    public DbSet<OrderItem> OrderItems { get; set; }

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

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<OrderItem>()
            .HasKey(o => o.Id);

        // 配置连接表关系
        modelBuilder.Entity<OrderItem>()
            .HasOne(o => o.Order)
            .WithMany(o => o.OrderItems)
            .HasForeignKey(o => o.OrderId);

        modelBuilder.Entity<OrderItem>()
            .HasOne(o => o.Product)
            .WithMany(p => p.OrderItems)
            .HasForeignKey(o => o.ProductId);
    }
}

// 查询操作
public List<OrderItem> GetOrderItemsByProductId(int productId)
{
    using (var context = new MyDbContext())
    {
        return context.OrderItems
            .Where(o => o.ProductId == productId)
            .ToList();
    }
}