"Sat, 17 Jan 1970 20:42:20"
Convert date and time to unixtime.
Another datetime format string at UTC
YYYYMMDD
19700117
Only TIME
20:42:20
General datetime
1970-01-17 20:42:20Z
For Database
1970-01-17 20:42:20
For HTTP1.1
Sat, 17 Jan 1970 20:42:20 GMT