Adjustment for Daylight Saving time

Question

Could anyone please help me on this:
our oracle dbtimezone is currently showing +00:00
our tables have date data type which store date and time as received from an external system sends date/time in UTC
How do I convert the UTC timestamp to BST (British Summer Time) while selecting from the table? I dont want to change the value in the table, just select it as BST.
I have tried different methods like new_time but no luck.
e.g.
select to_date('20120101 23:30:00','YYYYMMDD HH24:MI:SS'), new_time(to_date('20120101 23:30:00','YYYYMMDD HH24:MI:SS'), 'GMT','BST') from dual
returns
01/01/2012 23:30:00     01/01/2012 12:30:00
which I think is incorrect as the BST time should have been 1 hour ahead of GMT. But the above showss it to be 11 hrs behind. I am confused.
Could you please help.

Answer 1

user10237765 wrote:
How do I convert the UTC timestamp to BST (British Summer Time) Maybe like this?
with utc_dates as (
  select '20120101 22:30:00' t -- winter time in London = UTC = 22:00
  from dual union all
  select '20120601 22:30:00'  -- summer time in London is UTC advanced by 1 hour, so London time = 23:30
  from dual
  SELECT
         to_timestamp(t, 'yyyymmdd hh24:mi:ss' ) t,
         from_tz(   to_timestamp(t, 'yyyymmdd hh24:mi:ss' ),  '+0:00' ) tz_utc,
         from_tz(   to_timestamp(t, 'yyyymmdd hh24:mi:ss' ),  '+0:00' ) at time zone 'Europe/London' london_time
  from utc_dates
T                           TZ_UTC                             LONDON_TIME  
12/01/01 22:30:00,000000000 12/01/01 22:30:00,000000000 +00:00 12/01/01 22:30:00,000000000 EUROPE/LONDON
12/06/01 22:30:00,000000000 12/06/01 22:30:00,000000000 +00:00 12/06/01 23:30:00,000000000 EUROPE/LONDON
select
t, to_char( from_tz(   to_timestamp(t, 'yyyymmdd hh24:mi:ss' ),  '+0:00' ) at time zone 'Europe/London', 'hh24:mi:ss' ) hour
from utc_dates;
T                 HOUR    
20120101 22:30:00 22:30:00
20120601 22:30:00 23:30:00 Edited by: kordirko on 2012-01-27 02:12