• Subject: RE: AS400 Date Window For *MDY
  • From: "John Taylor" <john.taylor@xxxxxxxxxxxxxxx>
  • Date: Fri, 15 Oct 1999 18:48:42 -0600
  • Importance: Normal

Hi Jim,

Comments are inline.

> -----Original Message-----
> From: owner-midrange-l@midrange.com
> [mailto:owner-midrange-l@midrange.com]On Behalf Of Jim Langston
> Sent: Friday, October 15, 1999 4:53 PM
> To: MIDRANGE-L@midrange.com
> Subject: Re: AS400 Date Window For *MDY
>
>
> The fact is the "standard" on AS/400's is to use IBM's date
> field.  With the
> unwritten understanding that our logic should still work as long
> as we don't
> do anything "tricky" with it.  Put in a date and do simple math
> and functions
> on it and it becomes a black box.


Maybe my memory is failing, but I don't remember having date fields in the
database or RPG until V3R1 or V3R2. They weren't supported in display or
printer files until V4R3 or R4. I think it's a bit of a stretch to say that
the date data type is a standard in the AS/400 community. I think you'll
find many more instances of the date being defined as character or numeric.


> Being a black box, it makes absolutely no difference to us how IBM stores
> it.  IBM could decide to store it as the # of days since 010101
> if they wanted
> to and, in theory, our programs would still work.  If the OS
> stores a date as
> 32134 or 38291032 doesn't matter to me, as long as when I call
> for the date
> I get the same date that was entered originally.

Agreed. I don't have an issue with how IBM stores dates internally.

> When 2040 approaches, and IBM changes their OS to store dates differently,
> and they convert dates to the new method however they wish to do
> it (perhaps
> on the OS upgrade) my programs should still work, right?

Well, maybe. The problem is that you're making an assumption that IBM will
do this. This is what I would expect them to do as well. However, the reason
that I started the thread was to find out whether they will, or won't. As
currently documented, and generally acknowledged, the 6 digit date data type
will ONLY represent 01/01/1940 through 12/31/2039. It is a fixed window.

What if they DON'T change the range? Or, more likely, CAN'T change it
because the installed base has created applications that depend on the
existing behaviour?

I think we agree on how it SHOULD work, but everything I've seen in the
documentation indicates otherwise. Based on this, I'm going to avoid using
the date data type for 6 digit formats. A true shame, because they are
really handy when used for displays and printer files.


John Taylor


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