如何在一个模型中使用多个表？

from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship, sessionmaker

Base = declarative_base()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    orders = relationship("Order", back_populates="user")

class Order(Base):
    __tablename__ = 'orders'
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('users.id'))
    product = Column(String)
    user = relationship("User", back_populates="orders")

engine = create_engine('sqlite:///example.db')
Base.metadata.create_all(engine)
Session = sessionmaker(bind=engine)
session = Session()

# 添加数据
new_user = User(name='Alice')
new_order = Order(product='Widget', user=new_user)
session.add(new_user)
session.add(new_order)
session.commit()

# 查询数据
user = session.query(User).filter_by(name='Alice').first()
for order in user.orders:
    print(order.product)

from django.db import models

class User(models.Model):
    name = models.CharField(max_length=100)

class Order(models.Model):
    user = models.ForeignKey(User, related_name='orders', on_delete=models.CASCADE)
    product = models.CharField(max_length=100)