internal class OrderEntityTypeConfiguration : IEntityTypeConfiguration<Order>
    {
        public void Configure(EntityTypeBuilder<Order> builder)
        {            
            builder.ToTable("Orders", OrderingContext.DEFAULT_SCHEMA);//表名
            builder.HasKey(s => s.Id);//主键
            builder.Property(s => s.Id).ForSqlServerUseSequenceHiLo("ordersqu", OrderingContext.DEFAULT_SCHEMA);//主键自增规则
            builder.OwnsOne(s => s.Address);//一对一关系
            builder.Property<DateTime>("OrderDate").IsRequired();
            builder.Property<int?>("BuyerId").IsRequired(false);
            builder.Property<int>("OrderStatusId").IsRequired();
            builder.Property<int?>("PaymentMethodId").IsRequired(false);
            builder.Property<string>("Description").IsRequired(false);
            var nav = builder.Metadata.FindNavigation(nameof(Order.OrderItems));
            nav.SetPropertyAccessMode(PropertyAccessMode.Field);//取值方式
            builder.HasOne<PaymentMethod>()//一对多关系
                .WithMany()
                .IsRequired(false)
                .OnDelete(DeleteBehavior.Restrict);//删除模式
            builder.HasOne<Buyer>()
                .WithMany()
                .IsRequired(false)
                .HasForeignKey("BuyerId");
            builder.HasOne(s => s.OrderStatus)
                .WithMany()
                .HasForeignKey("OrderStatusId");
        }
    }