Multiple WordPress, One Database

Well, I have multiple wordpress installations and they all run on the same database. I want to define the database information in only one file, so i made a mysql.php in my root. I then put the information in the file,

define('DB_NAME', 'blog');    // The name of the database
define('DB_USER', 'blog');     // Your MySQL username
define('DB_PASSWORD', 'password'); // ...and password
define('DB_HOST', 'localhost');    // 99% chance you won't need to change this value
define('DB_CHARSET', 'utf8');
define('DB_COLLATE', '');

and then changed the wp-config file like the following where the mysql information was,
include '../mysql.php';

For some reason this doesn’t work.

Wordpress throws this error, Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can’t contact the database server at DB_HOST

Yet, all the info is correct.

Please help,
Eddyys