如何使用函数和sqlalchemy连接到数据库

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

engine = create_engine('数据库连接字符串')

Session = sessionmaker(bind=engine)

session = Session()

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String

Base = declarative_base()

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    email = Column(String)

Base.metadata.create_all(engine)

user = User(name='John', email='john@example.com')
session.add(user)
session.commit()

users = session.query(User).all()
for user in users:
    print(user.name, user.email)

user = session.query(User).filter_by(name='John').first()
user.email = 'new_email@example.com'
session.commit()

user = session.query(User).filter_by(name='John').first()
session.delete(user)
session.commit()