"Sun, 04 Jan 1970 21:49:21"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700104
Only TIME
21:49:21
General datetime
1970-01-04 21:49:21Z
For Database
1970-01-04 21:49:21
For HTTP1.1
Sun, 04 Jan 1970 21:49:21 GMT