OpenClass_database_query

CREATE TABLE `User` (
  `user_id` int,
  `username` varchar(50),
  `email` varchar(50),
  `password` varchar(50),
  PRIMARY KEY (`user_id`),
  KEY `Key` (`username`, `email`, `password`)
);

CREATE TABLE `Chatrooms` (
  `chatroom_id` int,
  `name_class` varchar(50),
  `pin_id` int,
  `user_id` int,
  PRIMARY KEY (`chatroom_id`),
  KEY `Key` (`name_class`, `pin_id`, `user_id`)
);

CREATE TABLE `Chatroom` (
  `chatroom_id` int,
  `message_id` int,
  `user_id` int,
  `timestamp` time,
  `message_con` varchar(300),
  PRIMARY KEY (`message_id`),
  KEY `FK` (`chatroom_id`, `user_id`),
  KEY `Key` (`timestamp`, `message_con`)
);