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* Originally created and last_mod by whom and when ?
@ 2007-11-14 11:06 Aarni Ruuhimäki <aarni@kymi.com>
0 siblings, 1 reply; 3+ messages in thread
From: Aarni Ruuhimäki @ 2007-11-14 11:06 UTC (permalink / raw)
To: pgsql-sql
Hello,
In a web app (Pg 8.2.4 + php) I have product and other tables with fields like
product_created timestamp without time zone
product_created_user_id integer
product_last_mod timestamp without time zone
product_last_mod_user_id integer
The person who last modified an item can obviously be someone else who
originally created it.
I can get the names and timestamps with two separate queries but how can I do
a single query to get the names of both ?
product_id | 1
...
product_created_user_id | 1
product_last_mod_user_id | 2
ID 1, created by X / date and time, last_mod by Y / date and time
And a similar query to only one table, users ?
user_id integer
user_forename text
...
user_created timestamp without time zone
user_created_user_id integer
user_last_mod timestamp without time zone
user_last_mod_user_id integer
ID 4, name Z, created by X / date and time, last_mod by Y / date and time
Join, sub select ? I tried some but only managed to get only one name, errors,
nothing at all or two rows with inner join + union ...
Lotsa thanks for any help,
Aarni
--
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Originally created and last_mod by whom and when ?
@ 2007-11-14 11:28 Richard Huxton <dev@archonet.com>
parent: Aarni Ruuhimäki <aarni@kymi.com>
0 siblings, 1 reply; 3+ messages in thread
From: Richard Huxton @ 2007-11-14 11:28 UTC (permalink / raw)
To: aarni@kymi.com; +Cc: pgsql-sql
Aarni Ruuhimäki wrote:
> Hello,
>
> In a web app (Pg 8.2.4 + php) I have product and other tables with fields like
>
> product_created timestamp without time zone
> product_created_user_id integer
> product_last_mod timestamp without time zone
> product_last_mod_user_id integer
>
> The person who last modified an item can obviously be someone else who
> originally created it.
>
> I can get the names and timestamps with two separate queries but how can I do
> a single query to get the names of both ?
Alias the tables, so you can join to the user-table twice.
SELECT p.*, u_cre.username as created_by, u_mod.username as modified_by
FROM
products p
LEFT JOIN
app_users u_cre ON p.product_created_user_id = u_cre.id
LEFT JOIN
app_users u_mod ON p.product_last_mod_user_id = u.mod.id
;
--
Richard Huxton
Archonet Ltd
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Originally created and last_mod by whom and when ?
@ 2007-11-14 12:39 Aarni Ruuhimäki <aarni@kymi.com>
parent: Richard Huxton <dev@archonet.com>
0 siblings, 0 replies; 3+ messages in thread
From: Aarni Ruuhimäki @ 2007-11-14 12:39 UTC (permalink / raw)
To: Richard Huxton <dev@archonet.com>; +Cc: pgsql-sql
On Wednesday 14 November 2007 13:28, Richard Huxton wrote:
> Aarni Ruuhimäki wrote:
> > Hello,
> >
> > In a web app (Pg 8.2.4 + php) I have product and other tables with fields
> > like
> >
> > product_created timestamp without time zone
> > product_created_user_id integer
> > product_last_mod timestamp without time zone
> > product_last_mod_user_id integer
> >
> > The person who last modified an item can obviously be someone else who
> > originally created it.
> >
> > I can get the names and timestamps with two separate queries but how can
> > I do a single query to get the names of both ?
>
> Alias the tables, so you can join to the user-table twice.
>
> SELECT p.*, u_cre.username as created_by, u_mod.username as modified_by
> FROM
> products p
> LEFT JOIN
> app_users u_cre ON p.product_created_user_id = u_cre.id
> LEFT JOIN
> app_users u_mod ON p.product_last_mod_user_id = u.mod.id
> ;
Charming ! Many thanks to you Richard.
Aarni
--
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2007-11-14 11:06 Originally created and last_mod by whom and when ? Aarni Ruuhimäki <aarni@kymi.com>
2007-11-14 11:28 ` Richard Huxton <dev@archonet.com>
2007-11-14 12:39 ` Aarni Ruuhimäki <aarni@kymi.com>
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