1. 获取标准时间格式

import datetime
today = datetime.datetime.today().strftime("%Y-%m-%d")

2. 当前时间加减N天

import datetime
today = datetime.datetime.today().strftime("%Y-%m-%d")
n = 1    # 加一天
m = -1    # 减一天
todat_n = (today + datetime.timedelta(days=n)).strftime("%Y-%m-%d")
todat_m = (today + datetime.timedelta(days=m)).strftime("%Y-%m-%d")