如何在Python中删除数据库记录？

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
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)

# 创建数据库引擎
engine = create_engine('sqlite:///example.db')
Base.metadata.create_all(engine)

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

# 删除一个用户
user_to_delete = session.query(User).filter_by(id=1).first()
if user_to_delete:
    session.delete(user_to_delete)
    session.commit()
else:
    print("User not found")

try:
    user_to_delete = session.query(User).filter_by(id=1).first()
    if user_to_delete:
        session.delete(user_to_delete)
        session.commit()
    else:
        print("User not found")
except Exception as e:
    session.rollback()
    print(f"An error occurred: {e}")

from sqlalchemy.orm import bulk_delete_mappings

# 假设我们要删除所有email以'@example.com'结尾的用户
users_to_delete = session.query(User).filter(User.email.like('%@example.com')).all()
bulk_delete_mappings(User, users_to_delete)
session.commit()

class Order(Base):
    __tablename__ = 'orders'
    id = Column(Integer, primary_key=True)
    user_id = Column(Integer, ForeignKey('users.id'))
    user = relationship('User', back_populates='orders')

class User(Base):
    __tablename__ = 'users'
    id = Column(Integer, primary_key=True)
    name = Column(String)
    email = Column(String)
    orders = relationship('Order', back_populates='user', cascade='all, delete-orphan')

# 删除一个用户及其所有订单
user_to_delete = session.query(User).filter_by(id=1).first()
if user_to_delete:
    session.delete(user_to_delete)
    session.commit()

from sqlalchemy import func

batch_size = 100
query = session.query(User).filter(User.email.like('%@example.com'))
total = query.count()

for offset in range(0, total, batch_size):
    batch = query.offset(offset).limit(batch_size).all()
    for user in batch:
        session.delete(user)
    session.commit()