#中間過程，一般都需要將字符串轉化為時間數組
time.strptime(a,'%Y-%m-%d %H:%M:%S')
>>time.struct_time(tm_year=2011, tm_mon=9, tm_mday=27, tm_hour=10, tm_min=50, tm_sec=0, tm_wday=1, tm_yday=270, tm_isdst=-1)

#將"2011-09-28 10:00:00"轉化為時間戳
time.mktime(time.strptime(a,'%Y-%m-%d %H:%M:%S'))
>>1317091800.0

#將時間戳轉化為localtime
x = time.localtime(1317091800.0)
time.strftime('%Y-%m-%d %H:%M:%S',x)
>>2011-09-27 10:50:00