Generate a table from period of time and each entry spans one hour

Question

For example I have 8am to 8pm.
I want the table where it can generate the table where it has entry one by one starttime and endtime (two columns):

8:00-9:00
9:00-10:00
....
19:00-20:00

Like this way. No date before the time.

Answer 1

You can use the generate_series function to do that:

psql# select generate_series('2014-01-01 16:00'::timestamp, '2014-01-01 20:00'::timestamp, '1 hour');
   generate_series   
---------------------
 2014-01-01 16:00:00
 2014-01-01 17:00:00
 2014-01-01 18:00:00
 2014-01-01 19:00:00
 2014-01-01 20:00:00
(5 rows)

And then you can use:

SELECT
    t AS starttime,
    t + INTERVAL '1 hour' as endtime
FROM
    GENERATE_SERIES(
        '2014-01-01 16:00'::TIMESTAMP,
        '2014-01-01 20:00'::TIMESTAMP,
        '1 hour'
    ) AS t

To get the start and end times.

Alternatively, to just get the times, you can use:

SELECT
    '08:00'::time + (t || ' hours')::interval as starttime,
    '08:00'::time + ((t + 1)::text || ' hours')::interval as endtime
FROM
    GENERATE_SERIES(0, 12) AS t

Answer 2

Simpler, use a full timestamp with a dummy date component and cast to time:

SELECT t::time  AS starttime
     , t::time + interval '1h' AS endtime
FROM   generate_series('2000-1-1 08:00'::timestamp
                     , '2000-1-1 19:00'::timestamp
                     , interval '1h') t;

The same for text columns:

SELECT to_char(t, 'HH24:MI') AS starttime
     , to_char(t + interval '1h', 'HH24:MI') AS endtime
FROM   generate_series('2000-1-1 08:00'::timestamp
                     , '2000-1-1 19:00'::timestamp
                     , interval '1h') t;