On 10/05/2018 15:30, Vlad Khorsun via Firebird-devel wrote: > > The key is that DST doesn't affect given time zone. TZ could be > "standard time" based (such as MSK) > or "DST based" (such as MSD or IST you speak about) but TZ itself is > not changed with DST start\end. > What is changed - is what TZ should be used. But we (I) speak not > about it. > That only in this scheme you linked, that is un-mappable to computers.
This scheme also has invalid date/tz. To convert a timestamp to UTC I need to known the timestamp and its timezone. So, I can't convert 2018-05-01 00:00 BRST (Brazilian Summer Time) to UTC, as there is no summer time in 2018-05-01, only standard time. And 2018-01-01 00:00 BRST + 4 months will not change to BRT (Brazilian Standard Time). This scheme just does not work! On the other hand, I can convert any timestamp in America/Sao_Paulo to UTC. I can add any interval to any America/Sao_Paulo timestamp and it will be already an America/Sao_Paulo timestamp. In fact the arithmetic is very simple, just add the interval to the stored UTC timestamp. When converting back to a string representation, it will be showed in America/Sao_Paulo time. Adriano ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
