如何在crud中进行更改后先检查数据库中的用户状态

SELECT status FROM users WHERE id = ?;

# 假设我们使用Python和SQLAlchemy
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

Base = declarative_base()

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

engine = create_engine('sqlite:///example.db')
Session = sessionmaker(bind=engine)
session = Session()

user_id = 1
user = session.query(User).filter_by(id=user_id).first()

if user.status == 'active':
    # 允许更改
    pass
else:
    # 不允许更改
    raise Exception("User is not active")

try:
    with session.begin():
        user = session.query(User).filter_by(id=user_id).with_for_update().first()
        if user.status == 'active':
            user.some_field = new_value
        else:
            raise Exception("User is not active")
except Exception as e:
    print(f"Error: {e}")

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

Base = declarative_base()

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

engine = create_engine('sqlite:///example.db')
Session = sessionmaker(bind=engine)
session = Session()

def update_user(user_id, new_value):
    try:
        with session.begin():
            user = session.query(User).filter_by(id=user_id).with_for_update().first()
            if user.status == 'active':
                user.some_field = new_value
            else:
                raise Exception("User is not active")
    except Exception as e:
        print(f"Error: {e}")

# 调用函数
update_user(1, "new data")