text: # article table DDL
  CREATE TABLE article
  (
    id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
    title VARCHAR(255),
    content TEXT,
    author VARCHAR(255),
    publish_time TIMESTAMP DEFAULT CURRENT_TIMESTAMP NOT NULL
  );
  
  
  # tag table DDL
  CREATE TABLE tag
  (
    id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
    name VARCHAR(32) NOT NULL,
    article_num INT(11) DEFAULT '0'
  );
  CREATE UNIQUE INDEX name ON tag (name);
  CREATE UNIQUE INDEX name_2 ON tag (name);
  
  
  # article_tag_relationship table DDL
  CREATE TABLE article_tag_relationship
  (
    id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
    article_id INT(11) NOT NULL,
    tag_id INT(11) NOT NULL
  );
  
  # user table DDL
  CREATE TABLE user
  (
    id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,
    username VARCHAR(32) NOT NULL,
    password VARCHAR(128),
    role VARCHAR(32)
  );
  CREATE UNIQUE INDEX username ON user (username);