如何删除sqlalchemy列上的自动更新？

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

Base = declarative_base()

class MyTable(Base):
    __tablename__ = 'my_table'
    id = Column(Integer, primary_key=True)
    name = Column(String(255), onupdate=None)  # 设置onupdate属性为None

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

Base = declarative_base()

class MyTable(Base):
    __tablename__ = 'my_table'
    id = Column(Integer, primary_key=True)
    name = Column(String(255), server_default=text("'default_value'"))  # 使用server_default属性覆盖自动更新的值