CREATE DATABASE sqltest;

#DROP DATABASE sqltest;
USE sqltest;

CREATE TABLE USER (
	id INT (10) UNSIGNED NOT NULL COMMENT 'Id',
	username VARCHAR (64) NOT NULL DEFAULT 'default' COMMENT '使用者名稱',
	PASSWORD VARCHAR (64) NOT NULL DEFAULT 'default' COMMENT '密碼',
	email VARCHAR (64) NOT NULL DEFAULT 'default' COMMENT '郵箱'
) COMMENT = '使用者表';

#複製表
CREATE TABLE vip_user AS
SELECT * FROM user;

DROP TABLE USER;

#新增列
ALTER TABLE user
ADD age int(3);
#刪除列
ALTER TABLE user
DROP COLUMN age;
#修改列
ALTER TABLE `user`
MODIFY COLUMN age tinyint;
#新增主鍵
ALTER TABLE user
ADD PRIMARY KEY (id);
#刪除主鍵
ALTER TABLE user
DROP PRIMARY KEY;