Python ORM SQLAlchemy核心操作

SQLAlchemy ORM映射数据库表。declarative_base声明基类。Column/Integer/String列定义。Session事务会话。query查询。filter过滤。join关联。relationship关系映射。session.commit/rollback。==惰性加载/eager加载。

from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.orm import declarative_base, Session, relationship

Base = declarative_base()
engine = create_engine('sqlite:///example.db', echo=True)

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

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

Base.metadata.create_all(engine)

with Session(engine) as session:
user = User(name="Alice", age=30)
session.add(user)
session.commit()

users = session.query(User).filter(User.age > 25).all()
for u in users:
print(u.name, u.age)