Re: Query from two tables return error

On 04/01/2016 06:52 AM, arnaud gaboury wrote:
>
>
> On Fri, Apr 1, 2016 at 3:33 PM, Sándor Daku <daku(dot)sandor(at)gmail(dot)com

>
> 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:
> 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
>
> And there, you have it.
>
> You can simply redefine the view.
>
> SELECT *,((mailusers.domain_name || '/'::text) ||
> mailusers.username) || '/'::text AS home_dir
> FROM email.mailusers;
>
>
> Thank you so much. This way I get all needed info in one view.

This might help understand what is going on:

http://www.postgresql.org/docs/9.5/interactive/tutorial-join.html

>
>
> 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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>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com