如何从数据库中获取键值

import mysql.connector

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

# 创建游标对象
cursor = cnx.cursor()

# 编写查询语句
query = "SELECT value FROM table_name WHERE key = 'your_key'"

# 执行查询
cursor.execute(query)

# 获取查询结果
result = cursor.fetchone()

# 处理查询结果
if result is not None:
    value = result[0]
    print("键值为:", value)
else:
    print("未找到对应的键值")

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