-- timezone abrev list
 select * from pg_timezone_names ; 

-- set timezone TO 'pg_timezone_names.name'
set timezone TO 'posix/Africa/Tunis'; --(GMT+01)
set timezone TO 'GMT'; --(UTC/GMT)

-- read current timezone:
SELECT  current_setting('TIMEZONE')

--reset timezone for database
alter database DATABASE_NAME set timezone TO 'posix/Africa/Tunis'; --(GMT+01)