WordPress: Use different MySQL login credentials depending on your host (localhost, sandbox, production, etc.)

get_real_host.php

<?php 

/* I use this in a separate config-properties.php  or otherwise named file
* which is then included by wp-config.php ~mj */

function getRealHost() {
	list($realHost,) = explode(':',$_SERVER['HTTP_HOST']);
	return $realHost;
}

$realHost = getRealHost();

$local_db = true;

if ( ($realHost === 'localhost') && ($local_db) ) {
	$db_name = 'local_db';
	$db_user = 'local_user'; 
	$db_pwd  = 'password';
	$db_host = 'ip_address'; 
} else if ( $realHost === 'sandbox.server' || $realHost === 'www.sandbox.server' ) {
	$db_name = 'sandbox_db'; 
	$db_user = 'sandbox_user'; 
	$db_pwd  = 'password';
	$db_host = 'ip_address';
} else if ( $realHost === 'production.server' || $realHost === 'www.production.server' ){
	$db_name = 'production_db'; 
	$db_user = 'production_user'; 
	$db_pwd  = 'password';
	$db_host = 'ip_address';
} else {
    $db_name = 'db_name';
    $db_user = 'root';
    $db_pwd  = 'root';
    $db_host = 'localhost';
}

define('DB_NAME', $db_name); //The name of your database. Note that this database must exist before running installer.php
define('DB_USER', $db_user); //Your database username
define('DB_PASSWORD', $db_pwd); //Your database users password
define('DB_HOST', $db_host); //The hostname for your database