建立SQLAlchemy中外键的Child和Parent之间的关系()有什么好处/坏处？

建立Child和Parent之间的关系()可以使查询更加容易，同时也能够避免手动实现join查询。但是如果关系没有正确建立，那么就有可能造成数据一致性的问题。 下面是一个建立Child和Parent之间直接关系()的例子：

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

Base = declarative_base()
engine = create_engine('sqlite:///:memory:', echo=True)
Session = sessionmaker(bind=engine)

class Parent(Base):
    __tablename__ = 'parent'
    id = Column(Integer, primary_key=True)
    children = relationship("Child", back_populates="parent")

class Child(Base):
    __tablename__ = 'child'
    id = Column(Integer, primary_key=True)
    parent_id = Column(Integer, ForeignKey('parent.id'))
    parent = relationship("Parent", back_populates="children")

Base.metadata.create_all(engine)

session = Session()

p1 = Parent()
session.add(p1)

c1 = Child()
c1.parent = p1

session.add(c1)

session.commit()

print(c1.parent) # <__main__.Parent object at 0x7f9b0cbc27d0>
print(p1.children) # [<__main__.Child object at 0x7f9b0cbc2710>]