text: CREATE TABLE `simple` (
    `seq` int(11) NOT NULL,
    `name` varchar(80) NOT NULL,
    `email` varchar(80) NOT NULL
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
  
  INSERT INTO `simple` (`seq`, `name`, `email`) VALUES
  (1, 'kim', 'kim@mail.com'),
  (2, 'lee', 'lee@mail.com');
  
  
  ALTER TABLE `simple`
    ADD PRIMARY KEY (`seq`);
  
  
  ALTER TABLE `simple`
    MODIFY `seq` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=3;