Проверка регистрации регистрации PHP AJAX

CREATE TABLE IF NOT EXISTS `users` (
`uid` int(11) NOT NULL AUTO_INCREMENT,
`user` varchar(255) DEFAULT NULL,
`pass` varchar(100) DEFAULT NULL,
`email` varchar(255) DEFAULT NULL,
`profile_photo` varchar(200) DEFAULT NULL,
PRIMARY KEY (`uid`),
UNIQUE KEY `username` (`user`),
UNIQUE KEY `email` (`email`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Grumpy Gannet