OCTom (11/5/2010)

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Hugo Kornelis (11/5/2010)

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OCTom (11/5/2010)

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Why would the two platforms differ by one day?

Probably because of February 29, 1900.

There is no such date. The full rule for leap years is not "evey four years", but "every four years, except every 100 years, except every 400 years". That is, a year is a leap year if it's divisible by 400, or if it's devisible by 4 but not by 100.

Some software companies blundered. For instance, very early versions of MS Excel thought Feb 29, 1900 existed. And since the internal storage of dates used the number of days since a base date, all versions since had no choice but to continue including this incorrect date. (Except if you choose the 1904-date system - in that case, you simply can't handle dates before Jan 1st, 1904 so it's not an issue anymore).

SQL Server uses the correct leap year rules. Feb 28th, 1900 corresponds to the integer 58, Mar 1st, 1900 to the integer 59, and ant attempt to operate on the date Feb 29th, 1900 results in an error.

So while I don't know anything about Infinium software or the AS/400, the one date difference you see suggests that this software has fallen victim to the same error that MS Excel has.

Thanks Hugo.