Re: [SQL] need some magic with generate_series()

From: Alexander Gataric <gataric(at)usa(dot)net>
To: "Andreas" <maps(dot)on(at)gmx(dot)net>, Filip Rembiałkowski <plk(dot)zuber(at)gmail(dot)com>
Cc: jan zimmek <jan(dot)zimmek(at)web(dot)de>, pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] need some magic with generate_series()
Date: 2013-01-23 00:08:54
Message-ID: 695Rawai22960M34@ca34.cms.usa.net
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I would create a common table expression with the series from Filip and left join to the table you need to report on.

Sent from my smartphone

----- Reply message -----
From: "Andreas" <maps(dot)on(at)gmx(dot)net>
To: "Filip Rembiałkowski" <plk(dot)zuber(at)gmail(dot)com>
Cc: "jan zimmek" <jan(dot)zimmek(at)web(dot)de>, <pgsql-sql(at)postgresql(dot)org>
Subject: [SQL] need some magic with generate_series()
Date: Tue, Jan 22, 2013 4:49 pm

Thanks Filip,
with your help I came a step further. :)

Could I do the folowing without using a function?

CREATE OR REPLACE FUNCTION month_series ( date )
RETURNS table ( monthnr integer )
AS
$BODY$

select to_char ( m, 'YYYYMM' )::integer
from generate_series ( $1, current_date, '1 month'::interval ) as m

$BODY$ LANGUAGE sql STABLE;

select project_id, month_series ( createdate )
from projects
order by 1, 2;

Am 22.01.2013 22:52, schrieb Filip Rembiałkowski:
> or even
>
> select m from generate_series( '20121101'::date, '20130101'::date, '1
> month'::interval) m;
>
>
>
> On Tue, Jan 22, 2013 at 3:49 PM, jan zimmek <jan(dot)zimmek(at)web(dot)de> wrote:
>> hi andreas,
>>
>> this might give you an idea how to generate series of dates (or other datatypes):
>>
>> select g, (current_date + (g||' month')::interval)::date from generate_series(1,12) g;
>>
>> regards
>> jan
>>
>> Am 22.01.2013 um 22:41 schrieb Andreas <maps(dot)on(at)gmx(dot)net>:
>>
>>> Hi
>>> I need a series of month numbers like 201212, 201301 YYYYMM to join other sources against it.
>>>
>>> I've got a table that describes projects:
>>> projects ( id INT, project TEXT, startdate DATE )
>>>
>>> and some others that log events
>>> events( project_id INT, createdate DATE, ...)
>>>
>>> to show some statistics I have to count events and present it as a view with the project name and the month as YYYYMM starting with startdate of the projects.
>>>
>>> My problem is that there probaply arent any events in a month but I still need this line in the output.
>>> So somehow I need to have a select that generates:
>>>
>>> project 7,201211
>>> project 7,201212
>>> project 7,201301
>>>
>>> It'd be utterly cool to get this for every project in the projects table with one select.
>>>
>>> Is there hope?
>>>
>>>
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>>
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