Question: My company uses a product that stores
date/time as an integer. I use a formula to convert it to a readable
date. I then need a function to convert the UNIX Epoch date format
into an Oracle display date format.
Answer: Oracle has several method for
converting an epoch date format into a displayable Oracle date, and
it depends on if you wish to keep timezone values:
select
to_timestamp_tz('1970-01-01 Europe/London', 'yyyy-mm-dd tzr')+
numtodsinterval(1241132400000/1000,'second') dstamp
from
dual;
You can also adjust epoch date conversion with the dbtimezone
and sessiontimezone variables, as well as
current_timestamp and and
time_zone variables:
alter database
set_time_zone = 'Europe/London';
select current_timestamp from dual;
You can also adjust an Epoch date for
daylight saving time adjustment.
For UNIX epoch date conversion examples, see MOSC note 340512.1
Try this example to convert a UNIX epoch date to a display value
with timestamp details:
select 'UTC' tz,
(cast((to_timestamp('01-02-2009 01:00:00','dd-mm-yyyy hh24:mi:ss'))
at time zone 'UTC' as date)
-
to_date('01-jan-1970','dd-mon-yyyy')) * (86400) * 1000 unix_time
from dual
union all
select 'GB' tz,
(cast((to_timestamp('01-02-2009 01:00:00','dd-mm-yyyy hh24:mi:ss'))
at time zone 'GB' as date)
-
to_date('01-jan-1970','dd-mon-yyyy')) * (86400) * 1000 unix_time
from dual
union all
select 'Etc/GMT+1' tz,
(cast((to_timestamp('01-02-2009 01:00:00','dd-mm-yyyy hh24:mi:ss'))
at time zone 'Etc/GMT+1' as date)
-
to_date('01-jan-1970','dd-mon-yyyy')) * (86400) * 1000 unix_time
from dual;
You can also create a function to convert an epoch date to a
display value:
create function
epoch_to_date( p_epoch in number)
return date
is
begin
return to_date('1970-01-01',
'YYYY-MM-DD') + (p_epoch/ 86400000); end
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