Question

Range for Oracle Date Data Type: “January 1, 4712 BC to December 31, 9999 AD”, Does the range has any logic behind it?
I mean the range has any historic significance or it has something related to programming and memory size etc.
I am just wondering, why only from January 1, 4712 BC to December 31, 9999 AD.

Answer 1

That’s the Julian date?

http://en.wikipedia.org/wiki/Julian_day

Wikipedia says 4713, hmm…off by 1…

I guess the upper limit is just because of the 4 digits.

Oracle doc says

http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/datatype.htm#i1847

Julian dates allow continuous dating
by the number of days from a common
reference. (The reference is
01-01-4712 years BCE, so current dates
are somewhere in the 2.4 million
range.)

EDIT

I guess the reason for 4712 instead of 4713 is that the conversion requires Y >= -4712:

http://en.wikipedia.org/wiki/Julian_day#Converting_Julian_calendar_date_to_Julian_Day_Number