Re: Query from two tables return error - Mailing list pgsql-general
| From | Sándor Daku |
|---|---|
| Subject | Re: Query from two tables return error |
| Date | |
| Msg-id | CAKyoTgaBm14mBuvAzhYHqATnEGKu=4uq1ocuYkpifS3GNDrVew@mail.gmail.com Whole thread Raw |
| In response to | Query from two tables return error (arnaud gaboury <arnaud.gaboury@gmail.com>) |
| Responses |
Re: Query from two tables return error
|
| List | pgsql-general |
On 1 April 2016 at 11:33, arnaud gaboury <arnaud.gaboury@gmail.com> wrote:
SELECT d.home_dir
FROM email.mail_dir d, email.mailusers u <- make a join between mail_dir and mailusers = join every(!) record from the first table with every(!) record from the second table
WHERE u.username='arnaud.gaboury'; <- but I need only those from the joined records where the username is arnaud.gaboury
What I am trying to do: I want the <home_dir> be returned for <username> u.I have one table email.mail.mailusers :I have one view email.mail_dir :
Table "email.mailusers"
Column | Type | Modifiers | Storage
| Stats target | Description
-------------+--------------------------+---------------------------------------------+--------
--+--------------+-------------
username | text | not null | extende
d | |
password | text | not null | extende
d | |
domain_name | text | not null default 'thetradinghall.com'::text | extende
d | |
created | timestamp with time zone | not null default now() | plain
| |
Indexes:
"mailusers_pkey" PRIMARY KEY, btree (username, domain_name)
Foreign-key constraints:
"mailusers_domain_fk" FOREIGN KEY (domain_name) REFERENCES email.domainlist(domain_name)
username | password | domain_name | created
----------------+--------------------------------------------------------------+---------------
arnaud.gaboury | XXXXYYYYYY | thetradinghall.com | 2016-02-04 09:48:58.834774+01
admin |XXXYYYYYY | thetradinghall.com | 2016-03-29 09:58:14.599743+02
postmaster | XXXYYYYYY | thetradinghall.com | 2016-03-31 16:36:18.96176+02
----------------------------------------------------------
View "email.mail_dir"
Column | Type | Modifiers | Storage | Description
----------+------+-----------+----------+-------------
home_dir | text | | extended |
View definition:
SELECT ((mailusers.domain_name || '/'::text) || mailusers.username) || '/'::text AS home_dir
FROM email.mailusers;
home_dir
------------------------------------
thetradinghall.com/arnaud.gaboury/
thetradinghall.com/admin/
thetradinghall.com/postmaster/
---------------------------------------------
One of many difficulties with computers that they do what you say them to do, not what you think or you think you are saying. :)
Lets see:
FROM email.mail_dir d, email.mailusers u <- make a join between mail_dir and mailusers = join every(!) record from the first table with every(!) record from the second table
WHERE u.username='arnaud.gaboury'; <- but I need only those from the joined records where the username is arnaud.gaboury
And there, you have it.
But it returns:
home_dir
------------------------------------
thetradinghall.com/arnaud.gaboury/
thetradinghall.com/admin/
thetradinghall.com/postmaster/
(3 rows)
You would have seen the problem, if you had used * instead d.homedir.
And there is no solution to your problem in the given circumstances.
You need the usename field in the view as well and then you can:
SELECT d.home_dir
FROM email.mail_dir d, email.mailusers u
FROM email.mail_dir d, email.mailusers u
WHERE u.username='arnaud.gaboury'
and u.usename=d.usename;
But it's completely unnecessary.
You can simply redefine the view.
SELECT *,((mailusers.domain_name || '/'::text) || mailusers.username) || '/'::text AS home_dir
FROM email.mailusers;
FROM email.mailusers;
Notice the * after the SELECT statement.
So you have all the data plus the homedir.
You can leave out the whole view thing and incorporate the home_dir expression right into your select.
Or you can write a function which makes this to you with the usename as argument.
Regards,
Sándor
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