使用python MySQL 实现一个 key-value(string:json) 读写库

在Python中，我们可以使用`pymysql`库（如果MySQL服务器版本较高，也推荐使用`mysql-connector-python`）来建立一个简单的key-value存储库，其中键是字符串，值是JSON格式的数据。这里我们创建一个基本的类来完成读写操作：

import pymysql.cursors
import jsonclass JsonKVStore:def __init__(self, host='localhost', db='test_db', user='root', password='', port=3306):self.conn = pymysql.connect(host=host,user=user,password=password,db=db,port=port,charset='utf8mb4',cursorclass=pymysql.cursors.DictCursor)def set_item(self, key, value):with self.conn.cursor() as cursor:query = "INSERT INTO kv_table (key, value) VALUES (%s, %s)"cursor.execute(query, (key, json.dumps(value)))self.conn.commit()def get_item(self, key):with self.conn.cursor() as cursor:query = "SELECT value FROM kv_table WHERE key=%s"cursor.execute(query, (key,))row = cursor.fetchone()if row:return json.loads(row['value'])else:return Nonedef update_item(self, key, new_value):with self.conn.cursor() as cursor:query = "UPDATE kv_table SET value=%s WHERE key=%s"cursor.execute(query, (json.dumps(new_value), key))self.conn.commit()def delete_item(self, key):with self.conn.cursor() as cursor:query = "DELETE FROM kv_table WHERE key=%s"cursor.execute(query, (key,))self.conn.commit()def close(self):self.conn.close()# 示例使用
store = JsonKVStore()
store.set_item('my_key', {'name': 'John', 'age': 30})
data = store.get_item('my_key')
store.update_item('my_key', {'name': 'Jane'})
store.delete_item('my_key')
store.close()

在这个库中，`set_item`、`get_item`、`update_item` 和 `delete_item` 方法分别对应设置、获取、更新和删除操作。