On Sat, Dec 5, 2009 at 11:11 AM, Jose Maria Terry Jimenez
<jtj@xxxxxxxxxxxxx> wrote:
> select distinct date_trunc('minute',"timestamp") as "timestamp" from
> historico order by "timestamp";
Notice the example from the documentation:
http://www.postgresql.org/docs/8.4/interactive/functions-datetime.html#FUNCTIONS-DATETIME-TRUNC
SELECT date_trunc('hour', TIMESTAMP '2001-02-16 20:38:40');
Result: 2001-02-16 20:00:00
In this case the keyword the second argument of the date_trunc() function is:
TIMESTAMP '2001-02-16 20:38:40'
This text is a special kind of cast that exists for time based datatypes.
This could be re-written as:
CAST( '2001-02-16 20:38:40' AS TIMESTAMP)
or
'2001-02-16 20:38:40'::TIMESTAMP
Other examples would be:
SELECT date_trunc( 'hour', now())
or
SELECT date_trunc( 'hour', myTimestampColumn)
FROM MyTable
LIMIT 1;
I hope this helps.
--
Regards,
Richard Broersma Jr.
Visit the Los Angeles PostgreSQL Users Group (LAPUG)
http://pugs.postgresql.org/lapug
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