python3.4 pymysql插入数据

import pymysql
conn = pymysql.connect(host='localhost', port=3306,user='root',passwd='root',db='DeliveryAddress',charset='UTF8')
cur = conn.cursor()
cur.execute("INSERT INTO `ProvinceCityCountyTown` VALUES ('3', '0', '上海')")
conn.commit()#这里是用conn提交的,很让人不解，为什么不用cur提交呢？害得我baidu都没找到例子，
cur.close()
conn.close()