给出数据库连接的封装类，实现连接数据库、执行sql命令的函数

为您提供以下示例代码，供参考：

import pymysql

class DBHandler():
    def __init__(self, host, port, user, password, database):
        self.host = host
        self.port = port
        self.user = user
        self.password = password
        self.database = database
        self.conn = self.connect_db()
        self.cursor = self.conn.cursor()

    def __del__(self):
        self.cursor.close()
        self.conn.close()

    def connect_db(self):
        conn = pymysql.connect(host=self.host, port=self.port, user=self.user,
                               password=self.password, database=self.database, charset='utf8')
        return conn

    def execute_sql(self, sql_query: str):
        try:
            self.cursor.execute(sql_query)
            self.conn.commit()
            return self.cursor.fetchall()
        except:
            self.conn.rollback()

if __name__ == '__main__':
    db = DBHandler('localhost', '3306', 'root', 'password', 'test_db')
    data = db.execute_sql("select * from user_info")
    print(data)

以上示例使用Python的pymysql库，实现了数据库连接及执行sql命令的功能。