"Sat, 31 Jan 1970 00:20:40"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700131
Only TIME
00:20:40
General datetime
1970-01-31 00:20:40Z
For Database
1970-01-31 00:20:40
For HTTP1.1
Sat, 31 Jan 1970 00:20:40 GMT