python如何实现事务机制

def transaction_test():
"""
事务演示
"""
conn, cursor = get_conn('testdb')
sql = "delete from employee where age > %s" % (20)
try:
   # 执行SQL语句
   cursor.execute(sql)
 
   # 这里以除0异常，来演示现实场景
   n = 1 / 0
 
   # 向数据库提交
   conn.commit()
 
except:
   # 发生错误时回滚
   print('事务回滚')
   conn.rollback()
 
cursor.close()
conn.close()