Innnterresssting
I found this on the net last week. I’ll go ahead and set this up for you since it is not obvious from the excerpt what this is about. There is a piece of software called Microsoft SQL Server that a lot of web servers use to provide content. For all I know, Xanga or Amazon.com could use it. There are competing products, such as MySQL, which is used by Google, but that is really beside the point. DateTime is a data type that is used by SQL Server to store, you guessed it, a date and time (ie, 08/15/1986 15:30:43). Due to size limitations, the span that can be represented by a DateTime variable must be limited. In other words, you couldn’t use one of these to represent the time of the Pharoahs or the year 3000. Anyway, not that it matters too much, but here you go:
Why is 1753 the earliest date for datetime?
Good question. It is for historical reasons. What we sometimes refer to as the western world, we have had two calendars in modern time: The Julian and the Gregorian calendars. These calendars were a number of days apart (depending on which century you look at), so when the culture that used the Julian calendar moved to the Gregorian calendar, they dropped from 10 to 13 days. Great Britain made this shift in 1752 (1752-09-02 were followed by 1752-09-14). The reasoning from Sybase to select 1753 as the earliest date was that if you were to store an earlier date than 1753, you would also have to know which country and also handle this 10-13 day jump. So they decided to not allow dates earlier than 1753. Note, however that other countries did the shift later than 1752. Turkey, for instance, did it as late as 1927.
Being Swedish, I find it a bit amusing that Sweden had the weirdest implementation. They decided to skip the leap day over a period of 40 years (from 1700 to 1740), and Sweden would be in sync with the Gregorian calendar after 1740 (but meanwhile not in sync with anyone). However, in 1704 and 1708 the leap day wasn’t skipped for some reason, so in 1712 which was a leap year, they inserted yet an extra day (imagine being born in Feb 30!) and then did the shift over a day like everyone else, in 1753.
