Advance use of CakePHP Virtual Fields

CakeModelConstruct

   /**
     * Constructor. Binds the model's database table to the object.
     *
     * @param integer|string|array $id Set this ID for this model on startup, can also be an array of options, see above.
     * @param string $table Name of database table to use.
     * @param string $ds DataSource connection name.
     */
    public function __construct($id = false, $table = null, $ds = null) {
        parent::__construct($id, $table, $ds);
        //verify that all children have a $role

        $this->virtualFields['name'] = sprintf('CONCAT(%s.first_name, " ", %s.last_name)', $this->alias, $this->alias);
        $this->virtualFields['initials'] = sprintf('CONCAT(UPPER(LEFT(%s.first_name,1)), UPPER(LEFT(%s.last_name,1)))', $this->alias, $this->alias);
        $this->virtualFields['last_schoolclass_visited'] = sprintf('(SELECT `user_settings`.`last_class_visited` FROM `user_settings` where `user_settings`.`user_id` = `%s`.`id`)', $this->alias);

    }