If we want to use different database credentials for the local development server and the online production or staging server, we can modify the database settings in the wp_config file http://blog.g-design.net/post/60019471157/managing-and-deploying-wordpress-with-git

config.php

if ($_SERVER['REMOTE_ADDR']=='127.0.0.1') {
    define('WP_ENV', 'development');
} else {
    define('WP_ENV', 'production');
}

// MySQL settings - You can get this info from your web host //
if (WP_ENV == 'development') {
    define('DB_NAME', 'mydb-dev');
    define('DB_USER', 'root');
    define('DB_PASSWORD', '');
    define('DB_HOST', 'localhost');
} else {
    define('DB_NAME', 'mydb-prod');
    define('DB_USER', 'username');
    define('DB_PASSWORD', 'pasdword');
    define('DB_HOST', 'mysql.mysite.com');
}