ALTER TABLE `tbl_digitalsignage_devices` ADD `linked_to_device` INT( 11 ) NULL ;

CREATE TABLE IF NOT EXISTS `tbl_notifications` (
`notification_id` bigint(20) NOT NULL,
  `action` varchar(255) DEFAULT NULL,
  `creation_time` datetime DEFAULT NULL,
  `last_update` datetime DEFAULT NULL,
  `message` varchar(255) DEFAULT NULL,
  `object_id` bigint(20) DEFAULT NULL,
  `receiver_id` bigint(20) DEFAULT NULL,
  `sender_id` bigint(20) DEFAULT NULL,
  `space_id` int(11) DEFAULT NULL,
  `state` varchar(255) DEFAULT NULL
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

ALTER TABLE `tbl_notifications`
 ADD PRIMARY KEY (`notification_id`);

ALTER TABLE `tbl_notifications`
MODIFY `notification_id` bigint(20) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=1;