如何获取单据_version的当前值

import mysql.connector

# 连接到数据库
cnx = mysql.connector.connect(user='username', password='password',
                              host='localhost', database='database_name')

# 创建游标对象
cursor = cnx.cursor()

# 执行查询语句
query = "SELECT _version FROM table_name WHERE id = 'document_id'"
cursor.execute(query)

# 获取查询结果
result = cursor.fetchone()

# 获取单据_version的当前值
current_version = result[0]

# 关闭游标和数据库连接
cursor.close()
cnx.close()

# 打印单据_version的当前值
print("当前单据_version的值为:", current_version)