如何将列添加到generate_series查询

Question

When looking a date ranges, is there anyway to have generate_series return the starting and ending dates as well?

select 
    '2014-06-05 00:00:00'::timestamp + ('1 month'::INTERVAL * s.a) AS date 
from 
    generate_series(1, cast(extract(month from age('2014-09-05'::date, '2014-06-05'::date)) AS integer), 1) as s(a);

Gives this output

date
2014-07-05 00:00:00
2014-08-05 00:00:00
2014-09-05 00:00:00

This is fine, however I would like to have

start_date     end_date       date
2014-06-05    2014-09-05    2014-07-05 00:00:00
2014-06-05    2014-09-05    2014-08-05 00:00:00
2014-06-05    2014-09-05    2014-09-05 00:00:00

The reason being is that I am extracting multiple start/end pairs from another table but cannot figure out a way of joining them together. I am also using PostgeSQL version 8.2.15 (hence the more complicated generate_series function).

To expand this to my primary problem, I have a table that contains these start and end time pairs.

    start_date         end_date
2014-08-25 00:00:00 2014-09-25 00:00:00
2014-05-16 00:00:00 2014-08-16 00:00:00
2014-09-09 00:00:00 2014-12-09 00:00:00
2014-06-05 00:00:00 2014-07-05 00:00:00
2014-05-19 00:00:00 2014-08-19 00:00:00
2014-05-15 00:00:00 2014-07-15 00:00:00
2014-09-04 00:00:00 2014-11-04 00:00:00

How can I iterate through this table and join it with the expanded date ranges?

Answer 1

Consider upgrading to a current version . Postgres 8.2 is long dead and forgotten.

For Postgres 8.2 (or later, but there are more elegant solutions in modern Postgres).

Assuming it's all about dates , not timestamps.

Providing start_date and end_date once :

SELECT start_date, end_date
     , (start_date + interval '1 month'
                   * generate_series(1, months))::date AS the_date
FROM  (  
   SELECT extract(month from age(end_date, start_date))::int AS months
        , start_date, end_date
   FROM (SELECT '2014-06-05'::date AS start_date
              , '2014-09-05'::date AS end_date
        ) data
   ) sub;

Using column name the_date instead of date which shouldn't be used as identifier.

Drawing values from table t instead:

SELECT start_date, end_date
     ,(start_date + interval '1 month'
                  * generate_series(1, months))::date AS the_date
FROM  (SELECT *, extract(month FROM age(end_date, start_date))::int AS months
       FROM   t) sub;

Without subquery

SELECT t_id, start_date, end_date
     ,(start_date + interval '1 month'
                  * generate_series(1, extract(month from age(end_date
                                                            , start_date))::int)
                  )::date AS the_date
FROM   t;

SQL Fiddle for Postgres 8.3.