It is really a database problem of managing all of the various rules of
different locations. Postgres has this built in. If you don't want to use
Postgres, you still might find the data you need to add to your 4D
implementation. See list below of 79 distinct zones.
John DeSoi, Ph.D.
> On Sep 26, 2018, at 8:17 AM, Pat Bensky via 4D_Tech <4d_tech@lists.4d.com>
> wrote:
>
> The only thing I'm not sure about is how various time zones change in their
> relationship to GMT (eg Summer Time etc.) For example if Country A is
> normally on GMT -8 but they're currently on Summer Time so 7AM in that time
> zone is CurrentHourGMT-8+1, how do we account for that?
postgres=# select distinct on (abbrev) * from pg_timezone_names;
name | abbrev | utc_offset | is_dst
-------------------------+--------+------------+--------
Atlantic/Azores | +00 | 00:00:00 | t
Etc/GMT-1 | +01 | 01:00:00 | f
Antarctica/Troll | +02 | 02:00:00 | t
Asia/Qatar | +03 | 03:00:00 | f
Iran | +0330 | 03:30:00 | f
Asia/Yerevan | +04 | 04:00:00 | f
Asia/Kabul | +0430 | 04:30:00 | f
Asia/Tashkent | +05 | 05:00:00 | f
Asia/Colombo | +0530 | 05:30:00 | f
Asia/Kathmandu | +0545 | 05:45:00 | f
Asia/Bishkek | +06 | 06:00:00 | f
Asia/Yangon | +0630 | 06:30:00 | f
Indian/Christmas | +07 | 07:00:00 | f
Asia/Ulaanbaatar | +08 | 08:00:00 | f
Australia/Eucla | +0845 | 08:45:00 | f
Asia/Chita | +09 | 09:00:00 | f
Etc/GMT-10 | +10 | 10:00:00 | f
Australia/Lord_Howe | +1030 | 10:30:00 | f
Pacific/Noumea | +11 | 11:00:00 | f
Pacific/Wake | +12 | 12:00:00 | f
Pacific/Chatham | +1245 | 12:45:00 | f
Etc/GMT-13 | +13 | 13:00:00 | f
Pacific/Kiritimati | +14 | 14:00:00 | f
Atlantic/Cape_Verde | -01 | -01:00:00 | f
Atlantic/South_Georgia | -02 | -02:00:00 | f
America/Rosario | -03 | -03:00:00 | f
America/La_Paz | -04 | -04:00:00 | f
Etc/GMT+5 | -05 | -05:00:00 | f
Etc/GMT+6 | -06 | -06:00:00 | f
Etc/GMT+7 | -07 | -07:00:00 | f
Etc/GMT+8 | -08 | -08:00:00 | f
Pacific/Gambier | -09 | -09:00:00 | f
Pacific/Marquesas | -0930 | -09:30:00 | f
Etc/GMT+10 | -10 | -10:00:00 | f
Etc/GMT+11 | -11 | -11:00:00 | f
Etc/GMT+12 | -12 | -12:00:00 | f
Australia/Adelaide | ACST | 09:30:00 | f
America/Moncton | ADT | -03:00:00 | t
Australia/Hobart | AEST | 10:00:00 | f
US/Alaska | AKDT | -08:00:00 | t
America/Guadeloupe | AST | -04:00:00 | f
Australia/Perth | AWST | 08:00:00 | f
Europe/Belfast | BST | 01:00:00 | t
Africa/Bujumbura | CAT | 02:00:00 | f
America/Chicago | CDT | -05:00:00 | t
Europe/Belgrade | CEST | 02:00:00 | t
Africa/Tunis | CET | 01:00:00 | f
America/Regina | CST | -06:00:00 | f
Pacific/Guam | ChST | 10:00:00 | f
Indian/Comoro | EAT | 03:00:00 | f
America/Indiana/Marengo | EDT | -04:00:00 | t
Europe/Sofia | EEST | 03:00:00 | t
Egypt | EET | 02:00:00 | f
Jamaica | EST | -05:00:00 | f
GMT0 | GMT | 00:00:00 | f
US/Aleutian | HDT | -09:00:00 | t
Hongkong | HKT | 08:00:00 | f
HST | HST | -10:00:00 | f
Asia/Jerusalem | IDT | 03:00:00 | t
Asia/Calcutta | IST | 05:30:00 | f
Japan | JST | 09:00:00 | f
Asia/Seoul | KST | 09:00:00 | f
America/Edmonton | MDT | -06:00:00 | t
MET | MEST | 02:00:00 | t
W-SU | MSK | 03:00:00 | f
America/Dawson_Creek | MST | -07:00:00 | f
Canada/Newfoundland | NDT | -02:30:00 | t
Pacific/Auckland | NZST | 12:00:00 | f
America/Ensenada | PDT | -07:00:00 | t
Asia/Karachi | PKT | 05:00:00 | f
Africa/Mbabane | SAST | 02:00:00 | f
Pacific/Pago_Pago | SST | -11:00:00 | f
UCT | UCT | 00:00:00 | f
Universal | UTC | 00:00:00 | f
Africa/Luanda | WAT | 01:00:00 | f
Africa/Casablanca | WEST | 01:00:00 | t
Asia/Pontianak | WIB | 07:00:00 | f
Asia/Jayapura | WIT | 09:00:00 | f
Asia/Makassar | WITA | 08:00:00 | f
(79 rows)
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