I agree with you Cadavre, but I realized that after posting and realizing the OP was saying devices instead of ids. I corrected it before I saw your new post.
Luis C.
General Disclaimer:
Are you seriously taking the advice and code from someone from the internet without testing it? Do you at least understand it? Or can it easily kill your server?
How to post data/code on a forum to get the best help: Option 1 / Option 2