url control

[quickstopman]

hey guys, i have a website thats a subdomain.

the problem is that i don't want people to get into the site through site.com/subdomain

i made a little script

but its not too effective

<?php
$url_thing = $_SERVER[HTTP_HOST];
if (!$url_thing == "flameable.getmetola.com") {
header("Location:http://flameable.getmetola.com");
}
?>

can someone help me make it more effective?

 

thanks!

[BlueSkyIS]

please define "effective".