Activerecord Relation With Mode Dependant Join

For one ‘chat’ record I have to find all ‘visitor’ records, which have any ‘message’.

I have this relation definition in Chat model class:

'visitorsWithMessages' => array(self::HAS_MANY, 'Visitor', 'chat_id',

	'join' => 'JOIN (SELECT DISTINCT visitor_id FROM message WHERE chat_id = :ypl0) cm ON (cm.visitor_id ='


See I had to insert ‘:ypl0’ to join clause. Can this query be rewritten in better way using Yii code?

(Earlier I had

'join' => 'JOIN message ON (visitor_id =', 'group' => ''

, but it was quite slow because of joining with whole ‘message’ table.)

Or can I use ‘create temporary table’ with Active Record relation?