Re: BUG #13691: Postgres reverse timezone system

dungdm93@live.com writes:
> The result is correct. So why Postgres reverse timezone system???

The problem is the conflict between POSIX-style time zone naming (in which
positive GMT offsets are west of Greenwich) and ISO-8601 time zone
notation (in which positive GMT offsets are east of Greenwich).  We follow
the ISO spec for data value input and output, but time zone names follow
the POSIX convention because that's what the Olson/IANA time zone database
does.  So the zone you are after is called "UTC-7" not "UTC+7".  There is
more info in the "Time Zones" section of our manual:
http://www.postgresql.org/docs/9.4/static/datatype-datetime.html#DATATYPE-TIMEZONES

As some wise man once said, the great thing about standards is there are
so many to choose from :-(

            regards, tom lane