Python connection mysql module

import json
from pymysql import *
class MysqlHelp(object):
    """mysql常用方法的封装"""
    myql_params = {
    
    
        "host": "localhost",
        "port": 3306,
        "database": "test",
        "user": "root",
        "password": "******",
        "charset": "utf8"
    }
    conn = Connection(**myql_params)  # 获取连接对象
    cr_obj = conn.cursor()  # 获取cursor对象

    @classmethod
    def get(cls, field, table_name, num):
        cls.cr_obj.execute("select %s from %s" % (field, table_name))
        if num == 1:
            return cls.cr_obj.fetchone()  # 获取一数据
        else:
            return cls.cr_obj.fetchall()  # 获取所有的数据

    @classmethod
    def insert(cls, table_name, field_name, field_value):
        st = ""
        for i in field_name:
            if i == field_name[-1]:
                st += "".join(i + ")")
            elif i == field_name[0]:
                st += "".join("(" + i + ",")
            else:
                st += "".join(i + ",")
        field_name = st
        sql = "insert into {}{} values{}".format(table_name, field_name, field_value)
        print(sql)
        ret = cls.cr_obj.execute("insert into {}{} values{}".format(table_name, field_name, field_value))
        print(ret)

    @classmethod
    def update(cls, table_name, field):
        field_name = field["field_name"]
        field_value = field["field_value"]
        c_field = field["c_field"]
        v_field = field["f_field"]

        field_value = "'" + field_value + "'"
        ret = cls.cr_obj.execute(
            "update {} set {}={} where {}={}".format(table_name, field_name, field_value, c_field, v_field))
        print(ret)

    @classmethod
    def delete(cls, table_name, field_name, field_value):
        field_value = "'" + field_value + "'"
        ret = cls.cr_obj.execute("delete from %s where %s = %s" % (table_name, field_name, field_value))
        print(ret)

    @classmethod
    def close(cls):
        cls.conn.commit()
        cls.cr_obj.close()
        cls.conn.close()


if __name__ == '__main__':
    mysqlHelp = MysqlHelp()
    keys = ['img', 'name', 'context']
    get_data = mysqlHelp.get("*", "comment", 0)
    get_data = [dict(zip(keys, item)) for item in get_data]
    print(get_data)

    # 写入json
    with open("./t1.json", "w", encoding='utf-8') as f:
        f.write(json.dumps(get_data, indent=4, ensure_ascii=False))

    mysqlHelp.close()