Hourly dates

Andrew Maclean wrote:

Is this the best way of getting a table of hourly dates?

-- How to generate a table of dates at hourly intervals between two dates.

-- select timestamp 'epoch' + generate_series * interval '1 second' as
dates from generate_series(extract(epoch from date_trunc('hour',
timestamp '2001-02-16 20:38:40'))::bigint,extract(epoch from
date_trunc('hour', timestamp '2001-02-17 20:38:40'))::bigint, 3600)
select generate_series * interval '1 second' + date_trunc('hour',
timestamp '2001-02-16 20:38:40') as dates
from generate_series(0,extract(epoch from(date_trunc('hour',
timestamp '2001-02-17 20:38:40') - date_trunc('hour', timestamp
'2001-02-16 20:38:40')))::bigint, 3600)

The commented out query seems to take into account the timezone which
is not what I want.

Andrew

Depends on what you have available as input. If you know the starting
time and number of records it's pretty easy:

Without time-zone:
select '2009-03-05 0100'::timestamp + generate_series(0,100) * '1
hour'::interval;
...
2009-03-07 23:00:00
2009-03-08 00:00:00
2009-03-08 01:00:00
2009-03-08 02:00:00
2009-03-08 03:00:00
2009-03-08 04:00:00
...

With time-zone info:
select '2009-03-05 0100'::timestamptz + generate_series(0,100) * '1
hour'::interval;
...
2009-03-07 23:00:00-08
2009-03-08 00:00:00-08
2009-03-08 01:00:00-08
2009-03-08 03:00:00-07
2009-03-08 04:00:00-07
2009-03-08 05:00:00-07
2009-03-08 06:00:00-07
...

Cheers,
Steve

Thanks for this, I can easily determine the number of records I want.

Andrew

On Tue, Jun 23, 2009 at 10:52 AM, Steve
Crawford<scrawford@pinpointresearch.com> wrote:

Andrew Maclean wrote:

Is this the best way of getting a table of hourly dates?

-- How to generate a table of dates at hourly intervals between two dates.

-- select timestamp 'epoch' + generate_series * interval '1 second' as
dates from generate_series(extract(epoch from date_trunc('hour',
timestamp '2001-02-16 20:38:40'))::bigint,extract(epoch from
date_trunc('hour', timestamp '2001-02-17 20:38:40'))::bigint, 3600)
select generate_series * interval '1 second' +  date_trunc('hour',
timestamp '2001-02-16 20:38:40') as dates
 from generate_series(0,extract(epoch from(date_trunc('hour',
timestamp '2001-02-17 20:38:40') - date_trunc('hour', timestamp
'2001-02-16 20:38:40')))::bigint, 3600)

The commented out query seems to take into account the timezone which
is not what I want.

Andrew

Depends on what you have available as input. If you know the starting time
and number of records it's pretty easy:

Without time-zone:
select '2009-03-05 0100'::timestamp + generate_series(0,100) * '1
hour'::interval;
...
2009-03-07 23:00:00
2009-03-08 00:00:00
2009-03-08 01:00:00
2009-03-08 02:00:00
2009-03-08 03:00:00
2009-03-08 04:00:00
...

With time-zone info:
select '2009-03-05 0100'::timestamptz + generate_series(0,100) * '1
hour'::interval;
...
2009-03-07 23:00:00-08
2009-03-08 00:00:00-08
2009-03-08 01:00:00-08
2009-03-08 03:00:00-07
2009-03-08 04:00:00-07
2009-03-08 05:00:00-07
2009-03-08 06:00:00-07
...

Cheers,
Steve

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--
___________________________________________
Andrew J. P. Maclean
Centre for Autonomous Systems
The Rose Street Building J04
The University of Sydney 2006 NSW
AUSTRALIA
Ph: +61 2 9351 3283
Fax: +61 2 9351 7474
URL: http://www.acfr.usyd.edu.au/
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