"Sun, 04 Jan 1970 00:39:40"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700104
Only TIME
00:39:40
General datetime
1970-01-04 00:39:40Z
For Database
1970-01-04 00:39:40
For HTTP1.1
Sun, 04 Jan 1970 00:39:40 GMT