UTC Definition
UTC represents the Coordinated Universal Time, formerly called Greenwich Mean Time, or GMT.
Formally, the value for a local time with respect to UTC is defined as follows:
UTC = local time - time_zone_displacement
where the value for time_zone_displacement is the time that must be subtracted from local time to produce the value for UTC, which is arbitrarily defined as zero hours displacement from the Greenwich meridian.
Using SET TIME ZONE
The following rules apply to using SET TIME ZONE.
- You can set the default time zone for a session or user by specifying either a numeric offset from UTC or by specifying a time zone string literal.
- The range of time zone displacements permissible is -12:59 through +14.00 inclusive.
- The form for time zone displacement values is INTERVAL HOUR TO MINUTE.
- The time zone string is associated with a session or user, not a time zone displacement. When a time zone displacement is needed in a request, that string plus a TIMESTAMP value or a TIME value, depending on which is appropriate, is used to determine the time zone displacement needed for a usage.