 -- Indexes for table `user`
 --
 ALTER TABLE `user`
-  ADD PRIMARY KEY (`user_id`);
+  ADD PRIMARY KEY (`user_id`),
+  ADD UNIQUE KEY `username_UNIQUE` (`username`);
 
 --
 -- Indexes for table `vaccination_record`

-- AUTO_INCREMENT for table `vaccine`
--
ALTER TABLE `vaccine`
  MODIFY `vaccine_id` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=0;
--
-- Constraints for dumped tables
--

  `address` varchar(255) DEFAULT NULL,
  `username` varchar(255) NOT NULL,
  `password` varchar(255) NOT NULL,
  `role` bit(1) NOT NULL,
  `avatar` text
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='User''s information table';

