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* join with an array
@ 2010-02-24 12:40 Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 13:09 ` Re: join with an array A. Kretschmer <andreas.kretschmer@schollglas.com>
0 siblings, 1 reply; 4+ messages in thread
From: Louis-David Mitterrand @ 2010-02-24 12:40 UTC (permalink / raw)
To: pgsql-sql
Hi,
I'm trying the following query:
select array_agg(t1.id) from table1 t1 join table2 t2 on (t2.id = any(array_agg)) group by t1.col1;
but I get this error: ERROR: column "array_agg" does not exist
I tried aliasing array_agg(t1.id) without success.
Thanks for any suggestions,
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: join with an array
2010-02-24 12:40 join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
@ 2010-02-24 13:09 ` A. Kretschmer <andreas.kretschmer@schollglas.com>
2010-02-24 13:34 ` Re: join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
0 siblings, 1 reply; 4+ messages in thread
From: A. Kretschmer @ 2010-02-24 13:09 UTC (permalink / raw)
To: pgsql-sql
In response to Louis-David Mitterrand :
> Hi,
>
> I'm trying the following query:
>
> select array_agg(t1.id) from table1 t1 join table2 t2 on (t2.id = any(array_agg)) group by t1.col1;
>
> but I get this error: ERROR: column "array_agg" does not exist
>
> I tried aliasing array_agg(t1.id) without success.
>
> Thanks for any suggestions,
I can't really understand what you want to achieve, but maybe this is
what you are looking for:
test=*# select * from a;
id | v
----+---
1 | 1
2 | 1
3 | 1
4 | 1
5 | 2
6 | 2
(6 rows)
test=*# select * from b;
id
----
1
3
(2 rows)
test=*# select array_agg(a.id), v from a join b on (b.id in (select a.id from a)) group by a.v;
array_agg | v
-------------------+---
{1,2,3,4,1,2,3,4} | 1
{6,5,5,6} | 2
(2 rows)
Question: you are 'pif' in the irc-channel?
Regards, Andreas
--
Andreas Kretschmer
Kontakt: Heynitz: 035242/47150, D1: 0160/7141639 (mehr: -> Header)
GnuPG: 0x31720C99, 1006 CCB4 A326 1D42 6431 2EB0 389D 1DC2 3172 0C99
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: join with an array
2010-02-24 12:40 join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 13:09 ` Re: join with an array A. Kretschmer <andreas.kretschmer@schollglas.com>
@ 2010-02-24 13:34 ` Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 14:39 ` Re: join with an array Achilleas Mantzios <achill@matrix.gatewaynet.com>
0 siblings, 1 reply; 4+ messages in thread
From: Louis-David Mitterrand @ 2010-02-24 13:34 UTC (permalink / raw)
To: pgsql-sql
On Wed, Feb 24, 2010 at 02:09:09PM +0100, A. Kretschmer wrote:
> In response to Louis-David Mitterrand :
> > Hi,
> >
> > I'm trying the following query:
> >
> > select array_agg(t1.id) from table1 t1 join table2 t2 on (t2.id = any(array_agg)) group by t1.col1;
> >
> > but I get this error: ERROR: column "array_agg" does not exist
> >
> > I tried aliasing array_agg(t1.id) without success.
> >
> > Thanks for any suggestions,
> I can't really understand what you want to achieve, but maybe this is
> what you are looking for:
Here is a test case I built. I want to list all cruises by cruise_type
but after merging cruise_type that have the same cruise_type_name:
drop table cruise;
drop table cruise_type;
create table cruise_type (
id_cruise_type serial primary key,
cruise_type_name text
);
create table cruise (
id_cruise serial,
id_cruise_type integer references cruise_type,
cruise_date timestamp default now()
);
insert into cruise_type (cruise_type_name) values
('5 day eastern carribean cruise'),
('5 day western carribean cruise'),
('5 day eastern carribean cruise'),
('5 day western carribean cruise')
;
insert into cruise (id_cruise_type) values
(1),
(2),
(3),
(4),
(1),
(2),
(3),
(4)
;
select array_agg(ct.id_cruise_type),ct.cruise_type_name from cruise_type ct join cruise c on (c.id_cruise = any(array_agg)) group by cruise_type_name;
^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: join with an array
2010-02-24 12:40 join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 13:09 ` Re: join with an array A. Kretschmer <andreas.kretschmer@schollglas.com>
2010-02-24 13:34 ` Re: join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
@ 2010-02-24 14:39 ` Achilleas Mantzios <achill@matrix.gatewaynet.com>
0 siblings, 0 replies; 4+ messages in thread
From: Achilleas Mantzios @ 2010-02-24 14:39 UTC (permalink / raw)
To: pgsql-sql
Στις Wednesday 24 February 2010 15:34:48 ο/η Louis-David Mitterrand έγραψε:
> Here is a test case I built. I want to list all cruises by cruise_type
> but after merging cruise_type that have the same cruise_type_name:
>
> drop table cruise;
> drop table cruise_type;
>
> create table cruise_type (
> id_cruise_type serial primary key,
> cruise_type_name text
> );
>
> create table cruise (
> id_cruise serial,
> id_cruise_type integer references cruise_type,
> cruise_date timestamp default now()
> );
>
> insert into cruise_type (cruise_type_name) values
> ('5 day eastern carribean cruise'),
> ('5 day western carribean cruise'),
> ('5 day eastern carribean cruise'),
> ('5 day western carribean cruise')
> ;
>
> insert into cruise (id_cruise_type) values
> (1),
> (2),
> (3),
> (4),
> (1),
> (2),
> (3),
> (4)
> ;
>
> select array_agg(ct.id_cruise_type),ct.cruise_type_name from cruise_type ct join cruise c on (c.id_cruise = any(array_agg)) group by cruise_type_name;
>
You dont specify (in english) what you exactly want to achive, but here is my shot:
1st, get the cruises by cruise type:
select ct.id_cruise_type,array_agg(c.id_cruise) as "List of Cruises" from cruise_type ct, cruise c WHERE c.id_cruise_type=ct.id_cruise_type GROUP BY ct.id_cruise_type ORDER BY ct.id_cruise_type;
id_cruise_type | List of Cruises
----------------+-----------------
1 | {1,5}
2 | {2,6}
3 | {3,7}
4 | {4,8}
(4 rows)
test=#
Then you may pretify this to include the name of each cruise type as well:
select ct.id_cruise_type,ct.cruise_type_name,array_agg(c.id_cruise) as "List of Cruises" from cruise_type ct, cruise c WHERE c.id_cruise_type=ct.id_cruise_type GROUP BY ct.id_cruise_type,ct.cruise_type_name ORDER BY ct.id_cruise_type;
id_cruise_type | cruise_type_name | List of Cruises
----------------+--------------------------------+-----------------
1 | 5 day eastern carribean cruise | {1,5}
2 | 5 day western carribean cruise | {2,6}
3 | 5 day eastern carribean cruise | {3,7}
4 | 5 day western carribean cruise | {4,8}
(4 rows)
EXERCISE:
Why cant we exclude ct.id_cruise_type from the select clause and group by of the above query?
--
Achilleas Mantzios
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2010-02-24 12:40 join with an array Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 13:09 ` A. Kretschmer <andreas.kretschmer@schollglas.com>
2010-02-24 13:34 ` Louis-David Mitterrand <vindex+lists-pgsql-sql@apartia.org>
2010-02-24 14:39 ` Achilleas Mantzios <achill@matrix.gatewaynet.com>
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