[Dismounted]

Clean your variables using the vBulletin Input Cleaner (Search Articles) and use the vBulletin Database functions.

PHP Code:

$result = $vbulletin->db->query_read("QUERY");
$result = $vbulletin->db->query_first("QUERY");
$result = $vbulletin->db->fetch_array($result);
$vbulletin->query_write("QUERY"); 


There are many more, but those are the most common used ones.