Date, time, timestamp
For operations that use date, time, or timestamp type data, the value is
converted to the real value based on the value 1970-01-01:00:00:00
(using
Coordinated Universal Time).
For the date, the value represents the number of days, based on the value
1970-01-01
(using Coordinated Universal Time).
For the time, the value represents the number of seconds at 24 hours.
For the timestamp, the value represents the number of seconds based on the value
1970-01-01:00:00:00
(using Coordinated Universal Time).