How to change the special variable $ZTIMESTAMP to your local time zone |

Article

Tomoko Furuzono · Jul 4, 2024 1m read

#ObjectScript #Tips & Tricks #InterSystems IRIS #Caché #Ensemble #InterSystems IRIS for Health

InterSystems FAQ rubric

$ZTIMESTAMP returns the date and time in UTC format, so to change it to the local time zone, use the following system method:

$SYSTEM.Util.UTCtoLocalWithZTIMEZONE($ZTIMESTAMP)ObjectScript
ObjectScript

The above output will be in the format ddddd,sssss.fff.

ddddd: Same format as $HOROLOG dates
　sssss: An integer indicating the number of seconds elapsed since midnight on the current date
　fff: Variable number of digits indicating the fractional part of a second

* Similar to $HOROLOG, except that $HOROLOG does not include fractional seconds.

SAMPLES>write $SYSTEM.Util.UTCtoLocalWithZTIMEZONE($ZTIMESTAMP)," - ", $horolog,!
63895,64252.66 - 63895,64252
SAMPLES>write $ZDATETIME($SYSTEM.Util.UTCtoLocalWithZTIMEZONE($ZTIMESTAMP),8)
20151209 17:45:56
SAMPLES>write $ZDATETIME($ZTIMESTAMP,8)
20151209 08:46:05
SAMPLES>ObjectScript
ObjectScript

Go to the original post written by @Tomoko Furuzono

Robert Cemper · Jul 4, 2024

Manipulating time values is a risky ground. See this simple example.

USER>write ?1%, $ZTZ," : ",$zdt($ZTS)," : ",$zdt($now())," : ",$zdt($h)
               -60 : 07/04/2024 16:03:42 : 07/04/2024 17:03:42 : 07/04/2024 18:03:42ObjectScript
ObjectScript

$ZTZ is the geographic offset to UTC in minutes
$ZTS is UTC time (no daylight saving !)
$NOW() is UTC adjusted by $ZTZ (no daylight saving or special time zone adjustment)
$H is based on the time set in your server OS

So for international applications using anything else than UTC is an open trap you might be caught in.

This was the original motivation to use UTC in ENSEMBLE and it's descendants and followers

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