### 创建用于管理 MySQL 的 Python 类 为了实现一个简化与 MySQL 数据库交互的工具，可以设计如下所示的一个 `MySQLManager` 类。此类不仅封装了基本数据库操作方法，还提供了一个辅助函数来展示如何使用这些功能。 #### 定义 MySQLManager 类 此部分展示了类定义以及初始化连接的方法： ```python import mysql.connector from mysql.connector import Error class MySQLManager: """A simple tool for interacting with MySQL databases.""" def __init__(self, host, user, password, db_name=None): """ Initialize database connection. :param str host: Database server address :param str user: Username for authentication :param str password: Password for authentication :param str db_name: Optional name of the initial database to connect to """ try: self.connection = mysql.connector.connect( host=host, user=user, password=password, database=db_name ) if self.connection.is_connected(): print("Successfully connected to MySQL.") except Error as e: print(f"Error while connecting to MySQL: {e}") ``` #### 添加更改数据库的功能 考虑到可能需要在不同数据库之间切换的需求，在上述基础上增加了改变当前使用的数据库实例的方法[^1]： ```python def change_db(self, new_db_name): """ Switches the active database within an existing session. :param str new_db_name: Name of target database """ cursor = self.connection.cursor() use_database_query = f"USE `{new_db_name}`;" cursor.execute(use_database_query) print(f"Switched to '{new_db_name}' database successfully.") ``` #### 实现查询执行器和其他常用命令 为了让使用者更方便地发送 SQL 查询并获取结果，这里实现了几个实用的方法： ```python def execute_query(self, query, params=None): """ Executes given SQL statement and returns results or None on failure. :param str query: SQL command string :param tuple/list/dict params: Parameters required by prepared statements :return list/tuple/None: Query result set when applicable """ cursor = self.connection.cursor(dictionary=True) try: cursor.execute(query, params) rows = cursor.fetchall() return rows finally: cursor.close() def insert_record(self, table, columns, values): """ Inserts single record into specified table using provided column names & value tuples. :param str table: Target table name :param iterable columns: Column identifiers corresponding to inserted data points :param iterable values: Data items matching each respective field """ placeholders = ', '.join(['%s'] * len(values)) sql = "INSERT INTO %s (%s) VALUES (%s)" % ( table, ", ".join(columns), placeholders) cursor = self.connection.cursor() try: cursor.execute(sql, values) self.connection.commit() print("Record added successfully!") except Exception as ex: self.connection.rollback() raise ex finally: cursor.close() ``` #### 提供帮助信息的帮助函数 最后，加入了一项名为 `show_help()` 的成员函数，它能够向用户提供有关可用接口及其参数的信息： ```python @staticmethod def show_help(): """ Prints out available methods along with brief descriptions about their usages. """ help_text = ''' Available Methods: - **change_db(new_db_name)**: Changes current working DB schema. - **execute_query(query[,params])**: Runs arbitrary SELECT queries against the database returning all matched records. Supports parameterized inputs via optional second argument. - **insert_record(table,columns,values)**: Adds one row entry according to supplied fields and associated content.''' print(help_text) ``` 通过这种方式构建出来的 `MySQLManager` 将会是一个易于理解和应用的强大工具，极大地提高了开发效率的同时也降低了错误发生的可能性。