Python-datetime模块

import datetime  #引入datetime模块
now_time = datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S.%f')
now_time

2021-03-29 15:55:25.779830

import datetime  #引入datetime模块

str_to_datetime = lambda x : datetime.datetime.strptime(x, '%Y/%m/%d').strftime('%Y-%m-%d %H:%M:%S.%f')

x = '2021/3/29'
str_to_datetime(x)

2021-03-29 00:00:00.000000

>>> a = datetime.date(2017,3,22)
>>> a.__format__('%Y-%m-%d')
'2017-03-22'
>>> a.__format__('%Y/%m/%d')
'2017/03/22'
>>> a.__format__('%y/%m/%d')
'17/03/22'
>>> a.__format__('%D')
'03/22/17'