# !/usr/bin/env python3
# -*- coding: utf-8 -*-
# @Time : 2020/5/19 22:00
# @Author : "小多肉"
# @Email : 1021181701@qq.com
# @File : 面向对象之魔术方法.py
# @Software: PyCharm
"""TODO:
第一题：基于pymysql模块实现一个数据库操作的上下文管理器（目的：实现自动关闭连接对象和游标）
第二题：自定义一个列表类型，实现对象可以之间可以 使用 - 来进行操作
# 要求：如果一个对象减去另一个对象，则把和被减对象中一样的数据给删除掉
# 如下：
li1 = MyList([11, 22, 33, 44])
li2 = MyList([1, 22, ])
res = li1 - li2
# res 打印的结果为[11,33,44]
"""
import pymysql
class DBContext:
def __init__(self,
host=None,
port=3306,
user='root',
password='',
charset='utf8',
database=None,
**kwargs
):
self.conn = pymysql.connect(host=host,
port=port,
user=user,
password=password,
charset=charset,
database=database,
**kwargs
)
self.cursor = self.conn.cursor()
def __enter__(self):
return self.conn, self.cursor
def __exit__(self, exc_type, exc_val, exc_tb):
self.cursor.close()
self.conn.close()
class ListSub:
def __init__(self,li:list):
self.li = li
def __sub__(self, other):
for i in other.li:
if i in self.li:
self.li.remove(i)
return self.li
def __add__(self, other):
return self.li + other.li
if __name__ == '__main__':
print("----------------------第一题------------------------")
with DBContext(host="192.168.5.20",password="love520",database="love") as (my_conn,my_cursor):
sql = "select to_date('2020-12-01' ,'YYYY-MM-DD') - to_date('2020-05-20','YYYY-MM-DD') from dual;"
my_cursor.execute(sql)
my_conn.commit()
data = my_cursor.fetchone()
print(data)
print("----------------------第二题------------------------")
li1 = ListSub([11, 22, 33, 44])
li2 = ListSub([1, 22, ])
res = li1 - li2
print(res)
res2 = li1 + li2
print(res2)
