Hugo’s answer is mostly correct, but I’ll add a few key points: When you’re storing the customer’s time zone, do NOT store a numerical offset. As others have pointed out, the offset from UTC is only for a single point in time, and can easily change for DST and for other reasons. Instead, you should … Read more
Yes, the current time zone is cached. For a good reason, it avoids trouble with broken code that uses DateTime.Now to implement elapsed time measurement. Such code tends to suffer a heart-attack when the time suddenly changes by an hour or more. You will have to call System.Globalization.CultureInfo.ClearCachedData() to reset the cached value. The next … Read more
As Jimmy points out you can use timezone transitions, but this is not available on PHP <5.3. as dateTimeZone() is PHP>=5.2.2 but getTransitions() with arguments is not! In that case here is a function that can give you timezone data, including whether in DST or not. function timezonez($timezone=”Europe/London”){ $tz = new DateTimeZone($timezone); $transitions = $tz->getTransitions(); … Read more
No, UTC itself never has DST. It is the constant frame of reference other time zones are expressed relative to. From the Wikipedia UTC page: UTC does not change with a change of seasons, but local time or civil time may change if a time zone jurisdiction observes daylight saving time or summer time. For … Read more
This is the answer for the machine on which the question is being asked: TimeZone.getDefault().inDaylightTime( new Date() ); A server trying to figure this out for a client will need the client’s time zone. See @Powerlord answer for the reason why. For any particular TimeZone TimeZone.getTimeZone( “US/Alaska”).inDaylightTime( new Date() );
In C#: // Define the input values. string[] input = { “2013-11-03 00:45:00”, “2013-11-03 01:00:00”, “2013-11-03 01:15:00”, “2013-11-03 01:30:00”, “2013-11-03 01:45:00”, “2013-11-03 01:00:00”, “2013-11-03 01:15:00”, “2013-11-03 01:30:00”, “2013-11-03 01:45:00”, “2013-11-03 02:00:00”, }; // Get the time zone the input is meant to be interpreted in. TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById(“Eastern Standard Time”); // Create an array … Read more
I think that in order to answer that question, we should think about the benefits of using UTC to store timestamps. I personally think that the main benefit to that is that the time is always (mostly) guaranteed to be consistent. In other words, whenever the timezone is changed, or DST applied, you don’t get … Read more
You can use time.localtime and look at the tm_isdst flag in the return value. >>> import time >>> time.localtime() (2010, 5, 21, 21, 48, 51, 4, 141, 0) >>> _.tm_isdst 0 Using time.localtime(), you can ask the same question for any arbitrary time to see whether DST would be (or was) in effect for your … Read more
Answer is: It depends. In total your database has three time zones Your session time zone: SESSIONTIMEZONE This you can change by ALTER SESSION SET TIME_ZONE=… at any time. It is relevant for result of CURRENT_DATE LOCALTIMESTAMP CURRENT_TIMESTAMP It is also the target time zone when you do CAST({TIMESTAMP/DATE without any timezone} AS TIMESTAMP WITH … Read more
I’ve got it figured out for my purposes. I’ll summarize what I learned (sorry, these notes are verbose; they’re as much for my future referral as anything else). Contrary to what I said in one of my previous comments, DATETIME and TIMESTAMP fields do behave differently. TIMESTAMP fields (as the docs indicate) take whatever you … Read more