Best way to obtain username from userid

[Lynne]

Originally Posted by mangus580

What you describe sounds like an edit to a core file, is this true? I am really trying to avoid that if possible....

Nope, just a plugin as James describes below:

Originally Posted by James Birkett

Hooks are used to use custom code without having to edit source files.
Admin CP -> Plugins & Products -> Add New Plugin
Product: vBulletin
Hook: attachment_start
Title: Whatever you like
PHP Code: {Your code}
Plugin is Active: Yes

PHP Code:

$hook_query_fields = ",user.username ";
$hook_query_joins = join the user table here ;