Re: [firebird-support] Time zones
There are requests to implement Time zones in Firebird: http://tracker.firebirdsql.org/browse/CORE-694 http://tracker.firebirdsql.org/browse/CORE-909 These two are in the "Optional features" list for Firebird 4: https://www.firebirdsql.org/en/planning-board/ Best Regards Stefan -- Stefan Heymann, Tübingen, Germany
Re: [firebird-support] Time zones
On 12/01/17 14:09, Tim Ward t...@telensa.com [firebird-support] wrote: > Can someone point me in the right direction please? There have been many attempts to justify storing a time stamp complete with timezone directly in a time field, but the real answer is that it is always wrong. Store location data in addition to a UTC time stamp and that way you can always display a correct time, and more importantly correctly move a time when passing over a DST change. The one thing that is missing from the 'offset' supplied by a browser is any means of identifying if the offset will be the same next month. You need to know the correct time zone and not just the current offset which is why a time with an offset may be wrong half of the year. Another piece of the jigsaw is the problem of identifying what the current offset data is in relation to a timezone. If you have created a UTC normalized time and have a timezone which gives you an offset, then the DST rules change, you will only know of the change if you have recorded the version of the rule set you normalised the time with, and the current rule set. So timezone/version is the additional data that should be recorded once working with UTC normalized times. And if you are running a system supporting several time zones then the server clock should always be set to UTC time. Trying to calculate UTC then Local time from a server time that may also have DST variations creates no end3of edge cases :) Store all times as UTC unless you are ONLY working with one timezone, but even that is tricky if your time zone uses DST ... -- Lester Caine - G8HFL - Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk
Re: [firebird-support] Time zones
12.01.2017 15:09, Tim Ward t...@telensa.com [firebird-support] wrote: > Can someone point me in the right direction please? Firebird does not handle time zones at all. CURRENT_TIMESTAMP and CURRENT_TIME return local time. -- WBR, SD. ++ Visit http://www.firebirdsql.org and click the Documentation item on the main (top) menu. Try FAQ and other links from the left-side menu there. Also search the knowledgebases at http://www.ibphoenix.com/resources/documents/ ++ Yahoo Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/firebird-support/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/firebird-support/join (Yahoo! ID required) <*> To change settings via email: firebird-support-dig...@yahoogroups.com firebird-support-fullfeatu...@yahoogroups.com <*> To unsubscribe from this group, send an email to: firebird-support-unsubscr...@yahoogroups.com <*> Your use of Yahoo Groups is subject to: https://info.yahoo.com/legal/us/yahoo/utos/terms/
Re: [firebird-support] Time zones
On 12-1-2017 15:09, Tim Ward t...@telensa.com [firebird-support] wrote: > Sorry if this is a really basic question, but some time spent searching > has failed to find for me the definitive detailed documentation on > exactly how Firebird handles time zones (I'm particularly interested, to > start with, in using CURRENT_TIMESTAMP to create a value in a TIMESTAMP > field, and later reading it out and using it to display in a UI, but > that's only to start with). > > Can someone point me in the right direction please? > Basically, Firebird doesn't really do anything with time zones, Firebird uses the timezone of the server for current_timestamp, current_time and current_date (and 'today' and 'now'). Timestamps (etc) in Firebird have no time zone information, so it is not possible to distinguish between say today 12:00 in UTC or UTC+1. This is important to realize if you access or write dates from systems in another time zone. For example the JDBC specification requires that times are handled in the timezone of the JVM, so if Firebird server is in UTC and the JVM is in UTC+1 you will get discrepancies when using `current_timestamp` in Firebird and things like `LocalDate.now()` on the Java side. PS In the future, could you start a new message instead of replying to an existing thread. In my mail client this message is grouped under the "FB 2.5 migrate to 3.0" thread instead of its own. -- Mark Rotteveel
[firebird-support] Time zones
Sorry if this is a really basic question, but some time spent searching has failed to find for me the definitive detailed documentation on exactly how Firebird handles time zones (I'm particularly interested, to start with, in using CURRENT_TIMESTAMP to create a value in a TIMESTAMP field, and later reading it out and using it to display in a UI, but that's only to start with). Can someone point me in the right direction please? -- Tim Ward
