Thread: Generating Rows from a date and a duration

Hi List,

I'm kinda stuck situation, I have a timestamp which resambles a
startdate and a duration in days and I want to bloat this, so I have a
row for every day beginning from the startdate. I have created an
example bellow, maybe I'm doing it on the wrong angle and you can come
up with some better ideas:

BEGIN TRANSACTION;

CREATE TABLE example
(  id serial NOT NULL,  startdate timestamp without time zone,  duration int_unsigned NOT NULL,  CONSTRAINT
pq_example_idPRIMARY KEY (id) 
) WITH (OIDS=FALSE)
;

insert into example(id,startdate,duration) values (1,'2010-09-03',4);
insert into example(id,startdate,duration) values (2,'2010-09-03',6);

CREATE OR REPLACE FUNCTION bloat_duration(IN id integer,                                         IN startdate
timestamp
without time zone,                  IN duration integer,                  OUT id integer,                  OUT
duration_datedate)   RETURNS SETOF RECORD AS 
$$
BEGIN RETURN QUERY SELECT
id,to_date(to_char(startdate,'YYYY-MM-DD'),'YYYY-MM-DD')+s.a AS
stockdate FROM generate_series(0,duration-1) AS s(a);
END;
$$
LANGUAGE 'plpgsql';

-- This works, but not what I want
SELECT * FROM bloat_duration(1,'2010-09-03',4);

-- This does not work

SELECT * FROM example AS ex
INNER JOIN bloat_duration(ex.id,ex.startdate,ex.duration) AS bd ON bd.id
= ex.id

ROLLBACK TRANSACTION;


greetings

Tim

Hi Brian, Hi List,


At Sat, 4 Sep 2010 09:20:53 -0400,
Brian Sherwood wrote:

> On Fri, Sep 3, 2010 at 5:40 AM, Tim Schumacher <
> tim.daniel.schumacher@gmail.com> wrote:
> 
> > I'm kinda stuck situation, I have a timestamp which resambles a
> > startdate and a duration in days and I want to bloat this, so I have a
> > row for every day beginning from the startdate. I have created an
> > example bellow, maybe I'm doing it on the wrong angle and you can come
> > up with some better ideas:
> >
> > BEGIN TRANSACTION;
> >
> > CREATE TABLE example
> > (
> >   id serial NOT NULL,
> >   startdate timestamp without time zone,
> >   duration int_unsigned NOT NULL,
> >   CONSTRAINT pq_example_id PRIMARY KEY (id)
> > ) WITH (OIDS=FALSE)
> > ;
> >
> > insert into example(id,startdate,duration) values (1,'2010-09-03',4);
> > insert into example(id,startdate,duration) values (2,'2010-09-03',6);
> >
> > CREATE OR REPLACE FUNCTION bloat_duration(IN id integer,
> >                                          IN startdate  timestamp
> > without time zone,
> >                                          IN duration integer,
> >                                          OUT id integer,
> >                                          OUT duration_date date)
> >    RETURNS SETOF RECORD AS
> > $$
> > BEGIN
> >  RETURN QUERY SELECT
> > id,to_date(to_char(startdate,'YYYY-MM-DD'),'YYYY-MM-DD')+s.a AS
> > stockdate FROM generate_series(0,duration-1) AS s(a);
> > END;
> > $$
> > LANGUAGE 'plpgsql';
> >
> > -- This works, but not what I want
> > SELECT * FROM bloat_duration(1,'2010-09-03',4);
> >
> > -- This does not work
> >
> > SELECT * FROM example AS ex
> > INNER JOIN bloat_duration(ex.id,ex.startdate,ex.duration) AS bd ON bd.id
> > = ex.id
> >
> > ROLLBACK TRANSACTION;

> Take a look at the generate_series function in the "set returning functions"
> section of the manual.
> http://www.postgresql.org/docs/8.4/interactive/functions-srf.html

As you can see in my example, I'm already using it and this is my
dilemma. Since I can not bring the values of the FROM-Table to the
parameters of my function.

Greetings

Tim

-- 
Compassion -- that's the one things no machine ever had.  Maybe it's
the one thing that keeps men ahead of them.               -- McCoy, "The Ultimate Computer", stardate 4731.3

On 09/08/2010 08:24 AM, Tim Schumacher wrote:
>>> I'm kinda stuck situation, I have a timestamp which resambles a
>>> startdate and a duration in days and I want to bloat this, so I have a
>>> row for every day beginning from the startdate. I have created an
>>> example bellow, maybe I'm doing it on the wrong angle and you can come
>>> up with some better ideas:

<snip>

> As you can see in my example, I'm already using it and this is my
> dilemma. Since I can not bring the values of the FROM-Table to the
> parameters of my function.

Depending on how large your base table is, this might work for you:

CREATE TABLE example
( id serial NOT NULL, startdate timestamp without time zone, duration int NOT NULL, CONSTRAINT pq_example_id PRIMARY
KEY(id) 
);

insert into example(id,startdate,duration) values (1,'2010-09-03',4);
insert into example(id,startdate,duration) values (2,'2010-09-03',6);

CREATE OR REPLACE FUNCTION unroll_durations()
RETURNS TABLE( example_id integer, duration_date date)
AS $$
DECLARE rec1         record; rec2         record;
BEGIN FOR rec1 IN SELECT id, startdate, duration             FROM example LOOP   FOR rec2 IN SELECT
to_date(to_char(rec1.startdate,'YYYY-MM-DD'),'YYYY-MM-DD') + s.a as
stockdate               FROM generate_series(0, rec1.duration - 1) AS s(a)   LOOP     example_id    := rec1.id;
duration_date:= rec2.stockdate;     RETURN NEXT;   END LOOP; END LOOP; 
END;
$$ LANGUAGE plpgsql;

select * from unroll_durations();example_id | duration_date
------------+---------------         1 | 2010-09-03         1 | 2010-09-04         1 | 2010-09-05         1 |
2010-09-06        2 | 2010-09-03         2 | 2010-09-04         2 | 2010-09-05         2 | 2010-09-06         2 |
2010-09-07        2 | 2010-09-08 
(10 rows)

HTH,

Joe

--
Joe Conway
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