How can I test this code?

I have this php code that I want to test, where do I put the file? TIA:

<?php	$sql = "select a.ID,a.post_title,c.name as tag
			from $wpdb->posts a, $wpdb->term_relationships b, $wpdb->terms c, $wpdb->term_taxonomy d
			where a.ID = b.object_id
			and b.term_taxonomy_id = c.term_id
			and c.term_id = d.term_id
			and d.taxonomy = '$tax'
			and a.post_status='$stat'
			and a.ID = $post_id";
	$tags = $wpdb->get_results($sql);
?>