yfix/yf

<?php

return '
  `notification_id` int(11) NOT NULL,
  `receiver_id` int(11) NOT NULL,
  `receiver_type` enum(\'user_id\',\'admin_id\',\'user_id_tmp\') NOT NULL,
  `is_read` tinyint(4) NOT NULL DEFAULT \'0\',
  PRIMARY KEY (`notification_id`,`receiver_id`,`receiver_type`)
';