Re: Daylight Savings

"Chaim J Nussbaum" <chaim.nussbaum@...>

Thanks for the help. I'll try using a query so that Oracle can do the work.

-----Original Message-----
From: ajerison@... [mailto:ajerison@...]
Sent: March 21, 2000 10:13 AM
To: magicu-l@...
Subject: RE: [magicu-l] Daylight Savings

From: "Andy Jerison" <ajerison@...>


Here's the skinny on US daylight savings time:

Nearly all of Indiana is in the Eastern time zone, GMT-5. The southwestern
and northwestern parts of the state are in the Central time zone, GMT-6. The
part of Indiana that's in the Eastern time zone doesn't use daylight savings

Arizona is even more fun. The entire state is in the Mountain time zone,
GMT-7. The state in general doesn't use daylight time. The Navajo and Hopi
Indian reservations (an area larger than the New England states combined!),
which occupy about one-sixth of the state in the northeast corner, follow
their own rules; the Navajo reservation does use daylight time, while the
Hopi reservation, entirely surrounded by Navajo country, doesn't.

So, it you have clients in those areas, you really need to know the time
zone that each client occupies.

Andy Jerison

-----Original Message-----
n Behalf Of Thomas Martin
Sent: Monday, March 20, 2000 11:48 PM
To: magicu-l@...
Subject: Re: [magicu-l] Daylight Savings

From: Thomas Martin <tmartin@...>

At 3/20/2000 03:11 PM -0500, you wrote:
From: "Chaim J Nussbaum" <chaim.nussbaum@...>

Hello Group.

A client of mine is requesting that our system calculate
daylight savings
adjustments. This is needed for a payroll interface.
i.e. On the 2nd of April, 2000. Daylight Savings Time
starts at 2:00AM is
most US states. Therefore, my client wants us to adjust the total hours
worked of an employee, so that it reflects daylight savings.

At this point I'm considering writing a DLL to find out the
current time
adjustment. If any of you have experience with this problem, your input
would be appreciated.
Well, the whole DST thing (and timezones, for that matter), are a bit more
complicated that they initially seem.

The rules for DST are supposedly laid out in United States Code Title 15
Chapter 6 SubChapter 9.


"The states" shall do this, and the "The states" shall do that, and then
the very last paragraph defines "states":

"As used in this Act, the term ''State'' includes the District of
the Commonwealth of Puerto Rico, or any possession of the United States."

So, the rules laid down don't even apply to the 50 entities that we
recognize as States!! Anyway, my understanding is that Arizona doesn't
participate, and I KNOW from personal experience that a small part (the
southern tip) of Indiana doesn't participate in DST. Other than that, the
general rule is that is starts on the first Sunday in April and
ends on the
last Sunday of October. (In the U.S.)

Hope this helps. ;) Have fun!

One other thing. I don't know squat about Oracle, but I was under the
impression that the data/time fields were actually stored in CUT
(Coordinated Universal Time, a.k.a. GMT and/or ZULU), with a time zone
difference indicator as part of the value. If this is true, and
if the O/S
handles the DST change properly, your problem may not exist.
Date/Time End
minus Date/Time Start will correctly return the hours worked.

Sat, 01 Apr 2000 23:00:00 -0500 minus Sun, 02 Apr 2000 07:00:00
-0400 = 7

Tom Martin

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