SQL

timestamp with timezone postgres

foo=> SET TIMEZONE TO 'Japan';
SET
foo=> SELECT '2011-01-01 00:00:00'::TIMESTAMP;
      timestamp      
---------------------
 2011-01-01 00:00:00
(1 row)

foo=> SELECT '2011-01-01 00:00:00'::TIMESTAMP WITH TIME ZONE;
      timestamptz       
------------------------
 2011-01-01 00:00:00+09
(1 row)

foo=> SELECT '2011-01-01 00:00:00+03'::TIMESTAMP;
      timestamp      
---------------------
 2011-01-01 00:00:00
(1 row)

foo=> SELECT '2011-01-01 00:00:00+03'::TIMESTAMP WITH TIME ZONE;
      timestamptz       
------------------------
 2011-01-01 06:00:00+09
(1 row)

foo=> SET TIMEZONE TO 'Australia/Melbourne';
SET
foo=> SELECT '2011-01-01 00:00:00'::TIMESTAMP;
      timestamp      
---------------------
 2011-01-01 00:00:00
(1 row)

foo=> SELECT '2011-01-01 00:00:00'::TIMESTAMP WITH TIME ZONE;
      timestamptz       
------------------------
 2011-01-01 00:00:00+11
(1 row)

foo=> SELECT '2011-01-01 00:00:00+03'::TIMESTAMP;
      timestamp      
---------------------
 2011-01-01 00:00:00
(1 row)

foo=> SELECT '2011-01-01 00:00:00+03'::TIMESTAMP WITH TIME ZONE;
      timestamptz       
------------------------
 2011-01-01 08:00:00+11
(1 row)

postgres insert timestamp without timezone

            
                
            
         INSERT INTO timestamp_demo (ts, tstz)
VALUES('2016-06-22 19:10:25-07','2016-06-22 19:10:25-07');Code language: SQL (Structured Query Language) (sql)

postgres insert timestamp without timezone

            
                
            
         CREATE TABLE timestamp_demo (
    ts TIMESTAMP, 
    tstz TIMESTAMPTZ
);Code language: SQL (Structured Query Language) (sql)

postgresql change timezone on timestamp without timezone

-- You have an issue where entries in the database are recorded in local time without the timezone
-- Postgresql assumes that these entries are in fact UTC
-- This corrects these entries by converting them to actual UTC
-- You might want to update the column (from timestamp) to a timestamptz, then perform the command below
UPDATE <table>
SET <timestamptz_field> = 
  (<timestamptz_field> AT TIME ZONE 'UTC') AT TIME ZONE '<correct_time_zone>';
  
-- e.g start_date_time before = '2021-07-29 18:15:16+00' (This is from a location at GMT+2)
-- start_date_time after = '2021-07-29 16:15:16+00' (This is the actual UTC timestamp)
UPDATE public.uut_result
	SET start_date_time= (start_date_time at time zone 'utc') at time zone 'Africa/Harare'