[AccessD] Comparing times in different time zones

Kenneth W Van Huss kvanhuss at airrsystem.com
Mon Oct 24 23:37:23 CDT 2011


I found a table, but don't recall where, that has the offset for all the
countries with which I am currently dealing.  I added a field to the
location table that includes the UTC Offset.  So for Iraq, I take the local
time and convert it to UTC/GMT using the offset in the location table.  I
take the server time, US Central, and convert it to UTC/GMT.  Now I can
compare the time of the event against the time it was entered into the
database.  So right now as we write, the comparison is fine.  

But it will become a maintenance nightmare on an ongoing basis, I think
because these offsets change depending on time of year and Daylight Savings
Time.  Keeping in synch will be a real challenge.  What happens for example
if an event occurs the morning of transition to or from DST in a time zone
that just changed, and we need to compare it against server time 8 time
zones away, which has not yet switched to DST.  

I guess I can't see the forest for the trees right now and need some
clarity.   Any ideas are greatly appreciated.




-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Darryl Collins
Sent: Monday, October 24, 2011 10:27 PM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Comparing times in different time zones

Bloody hell Ken,

That is going to be a struggle to get right given all the Local time zones
you are going to need to deal with. Just in Oz alone it is a mess with some
states on Daylight saving time and other states ignore it.  This leads to
stupid situations where you will have two cities in the same zone being 1
hour apart.

I am sure Australia doesn't have a monopoly on this sort of weirdness.

I deal a lot with Asia and the US and Africa these days so I use this
website <<http://www.timeanddate.com/worldclock/>> to keep track of
different times, maybe it can help you out?

I guess it depends on where you are grabbing the offset from and if it is
automatically updated or not?


-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Kenneth W Van
Huss
Sent: Tuesday, 25 October 2011 2:13 PM
To: Access Developers discussion and problem solving
Subject: [AccessD] Comparing times in different time zones

I have an unmet challenge relating to comparing times in different time
zones.  User on the other side of the world, literally enters time of an
event.  When the user saves the record in the database that time is
captured, though the time is the server time, located in US central time
zone.  Using UTC offset I have "normalized" the times to UTC to compare
against one another to ensure the record was entered within a certain amount
of time.  The challenge I see down the road is Day Light Savings time and
the impact that will have on the offset.  Anyone experience this before?

 

Thanks!

Ken

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