text: -- create table user
  CREATE TABLE IF NOT EXISTS user (
      id int(10) unsigned NOT NULL AUTO_INCREMENT,
      client_public_key_hash BINARY(20) NOT NULL,
      client_public_key TEXT,
      server_private_key TEXT,
      created_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
      updated_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
      PRIMARY KEY (id),
      UNIQUE KEY client_public_key_hash (client_public_key_hash)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
  
  -- create table account
  CREATE TABLE IF NOT EXISTS account (
      id int(10) unsigned NOT NULL AUTO_INCREMENT,
      user_id int(10) unsigned DEFAULT NULL,
      ext_id VARCHAR(255) NOT NULL,
      provider int(10) unsigned NOT NULL,
      created_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP,
      updated_at datetime NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
      PRIMARY KEY (id),
      CONSTRAINT fk_account_user FOREIGN KEY (user_id) REFERENCES user(id),
      UNIQUE KEY ext_id (ext_id)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;