调取数据库文件

# 导入SQLAlchemy库from sqlalchemy import create_engine, Column, Integer, Stringfrom sqlalchemy.orm import sessionmakerfrom sqlalchemy.ext.declarative import declarative_base# 创建数据库连接engine = create_engine('mysql+pymysql://username:password@host/dbname')# 创建会话Session = sessionmaker(bind=engine)session = Session()# 定义数据模型Base = declarative_base()class User(Base):    __tablename__ = 'users'    id = Column(Integer, primary_key=True)    name = Column(String(50))    email = Column(String(50))# 查询数据users = session.query(User).all()for user in users:    print(user.id, user.name, user.email)# 关闭会话session.close()