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

Create a CTE with the project code and starting month of the project. Left join to month series CTE.

Sent from my smartphone

----- Reply message -----
From: "Andreas" <maps.on@gmx.net>
To: "Alexander Gataric" <gataric@usa.net>
Cc: "Filip Rembiałkowski" <plk.zuber@gmail.com>, "jan zimmek" <jan.zimmek@web.de>, <pgsql-sql@postgresql.org>
Subject: [SQL] need some magic with generate_series()
Date: Tue, Jan 22, 2013 7:00 pm


The query should work for all projects in the projects table where everyone has a seperate startdate for the series.
For the join I need ( project_id, month_nr ).

When I tried I couldn't figure out how to feed the startdate into Filip's expression without using the function to encapsulate the generate_series().
The folowing doesn't work:

select  project_id,
         (    select  to_char ( m, 'YYYYMM' )::integer
              from    generate_series ( projects.createdate, current_date, '1 month'::interval )   as  m
        )
from    projects
order by 1, 2;



Am 23.01.2013 01:08, schrieb Alexander Gataric:
> I would create a common table expression with the series from Filip > and left join to the table you need to report on.
>
> ----- Reply message -----
> From: "Andreas" <maps.on@gmx.net>
> To: "Filip Rembiałkowski" <plk.zuber@gmail.com>
> Cc: "jan zimmek" <jan.zimmek@web.de>, <pgsql-sql@postgresql.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.zimmek@web.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.on@gmx.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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>
>
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