级联数据库

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

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()

# 创建用户和订单
user = User(name='Alice')
order = Order(product='Book', user=user)
session.add(user)
session.commit()

# 更新用户信息
user.name = 'Alice Smith'
session.commit()  # 这将自动更新关联的订单信息

session.close()