Setting an external database for WordPress from wp_config file

Question

Problem:

How to use an external database, that is not located in localhost, by setting the WordPress configuration in the file wp_config.

So, all WordPress files (wp_content, wp_admin, ...) are in Local computer A, and the database is in Server B.

Can this be done ?, how would the settings be ?

What I have tried:

define('DB_HOST', 'example');
define('DB_HOST', 'example.com');
define('DB_HOST', 'http://example.com');
define('DB_HOST', 'example.com:22');

Notes:

The server is using MySQL on Linux.
When I change the configuration, to use a local database, it works perfect. So it is not WordPress, is the connection setting.
username, password, and database name (DB_NAME, DB_USER, DB_PASSWORD) are correct.

Current error:

Error establishing a database connection

Related links:

http://codex.wordpress.org/Editing_wp-config.php

Does the database user that you are using have permission to connect remotely? See this thread and this Stack Overflow question. — vvanasten
@wanasten sounds good, my first guess is that root has remote permissions, but I'm gonna check it, do you know how to check that ? — Francisco Corrales Morales
root probably doesn't have them by default. If you're using phpMyAdmin: log in and click the Users tab, the allowed hosts will be displayed in the Hosts column. — vvanasten

qkhanhpro qkhanhpro · Accepted Answer · 2018-07-24T03:20:10

To start the diagnosis, I would do the following :

Try to connect to the DB with the user you have from another device. If you can, we are able to rule out the connectivity problem / remote access right on the DB side. Be sure to allow the mySql listening port through any firewall you may have
define('DB_HOST', 'example.com:port'); is the correct format. Can you try to use the IP address? Also mySql listen on port 3306 by default.
Quite unlikely but also check the outbound connection from your WP host to the DB server / mySql port