Обсуждение: quick Date question

select '12/13/1901 18:00:00 CST'::datetime;
?column?                    
----------------------------
Fri Dec 13 18:00:00 1901 CST
(1 row)

select '12/13/1901 17:59:59 CST'::datetime;
?column?                
------------------------
Fri Dec 13 23:59:59 1901
(1 row)


Why???

> select '12/13/1901 18:00:00 CST'::datetime;
> ----------------------------
> Fri Dec 13 18:00:00 1901 CST
> select '12/13/1901 17:59:59 CST'::datetime;
> ------------------------
> Fri Dec 13 23:59:59 1901
> Why???

Unix time databases do not have support for dates earlier than 1903 (?)
since Unix system time does not go back farther than that. Also, it
would be inappropriate (imho) to adopt the current conventions for
timezone since those conventions did not exist back then.

So date/time outside of the Unix system time range is displayed as UTC.
You had forced a different time zone in your input, but the output is
the same time in the universal time zone. If you do not specify a time
zone then the output matches the input exactly.
                     - Tom