fix sql query

booking.helper.inc

@@ -699,7 +699,7 @@ function _booking_studygroup_cleanup()
 	//search for entries already in the mapping table that have a booking_status of 3 (not coming)
 	$to_remove_query = db_query("SELECT m.* FROM {booking_studygroup_mapping} m
 		 inner join {booking_person} p on p.nid = m.booking_node_id
-		 WHERE booking_eventid = :eid AND p.booking_status = 3", 
+		 WHERE m.booking_eventid = :eid AND p.booking_status = 3", 
 		array(':eid' => $event->eid));
 	$to_remove = $to_remove_query->fetchAll();