sqlalchemy插入数据不起作用

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

# 创建数据库引擎
engine = create_engine('sqlite:///example.db', echo=True)

# 创建基类
Base = declarative_base()

# 定义模型
class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    age = Column(Integer)

# 创建表
Base.metadata.create_all(engine)

# 创建会话
Session = sessionmaker(bind=engine)
session = Session()

# 插入数据
new_user = User(name='Alice', age=30)
session.add(new_user)

# 提交会话
session.commit()

# 关闭会话
session.close()

try:
    new_user = User(name='Bob', age=25)
    session.add(new_user)
    session.commit()
except Exception as e:
    session.rollback()  # 回滚会话
    print(f"Error occurred: {e}")
finally:
    session.close()

Base.metadata.create_all(engine)

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

new_user = User(name='Charlie', age=40)  # age 应该是整数类型

new_user = User(name='David', age=35)
session.add(new_user)
session.flush()  # 将数据写入数据库，但不提交事务
session.commit()  # 提交事务

Session = sessionmaker(bind=engine, autocommit=False)
session = Session()

users = [User(name='Eve', age=28), User(name='Frank', age=33)]
session.bulk_save_objects(users)
session.commit()