Session Time Zone

As the name implies, the session time zone can be different for each database attachment.It can be set explicitly in the DPB with the item isc_dpb_session_time_zone;otherwise, by default, it uses the same time zone as the operating system of the Firebird server process.This default can be overridden in firebird.conf, setting DefaultTimeZone.

Subsequently, the time zone can be changed to a given time zone using a SET TIME ZONE statement or reset to its original value with SET TIME ZONE LOCAL or ALTER SESSION RESET.

A time zone is specified as a string, either a time zone region (for example, 'America/Sao_Paulo') or a displacement from GMT in hours:minutes (for example, '-03:00').

A time/timestamp with time zone is considered equal to another time/timestamp with time zone if their conversions to UTC are equivalent.For example, time '10:00 -02:00' and time '09:00 -03:00' are equivalent, since both are the same as time '12:00 GMT'.