mysql 创建表注释

CREATE TABLE `users` (
  `id` INT UNSIGNED AUTO_INCREMENT PRIMARY KEY COMMENT '用户ID',
  `username` VARCHAR(50) NOT NULL UNIQUE COMMENT '用户名',
  `email` VARCHAR(100) NOT NULL UNIQUE COMMENT '电子邮件',
  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '更新时间'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COMMENT='用户表';

SHOW CREATE TABLE users;

ALTER TABLE users COMMENT '更新后的用户表注释';

ALTER TABLE users MODIFY COLUMN username VARCHAR(50) NOT NULL UNIQUE COMMENT '新的用户名注释';