Count Users with specific meta

You could try something like:

<?php
global $wpdb;
$number_of_users_with_facebook_url = $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->usermeta WHERE meta_key=%s", 'facebook_url' ) );
?>

Thanks for your suggestion!
It seem to work all though right now it counts everyones meta_value even if the value is empty. How would one adjust this to look for a specific value? If lets say the only options for “facebook_url” is Yes or No and we want to count all Yeses out there.

Thanks for your help

Some quick mysql online courses and I figured it out.
Thanks for your help. I put it all into a function like this:

function count_users_per_meta($meta_key, $meta_value)
{
	global $wpdb;
	$user_meta_query = $wpdb->get_var( $wpdb->prepare( "SELECT COUNT(*) FROM $wpdb->usermeta WHERE meta_key='$meta_key' AND meta_value='$meta_value'" ) );
	return number_format_i18n($user_meta_query);
}