Put DB Number

I have more than one domain on the server, where should I put this code? Topmost in Wp-Config.php or bottom? I also have cached html code in wp-config.php should this redis be put after or before? thanks.

define('WP_REDIS_DATABASE', 0);
define('WP_REDIS_DATABASE', 1);
define('WP_REDIS_DATABASE', 2);