CREATE TABLE users (
  username VARCHAR(30) NOT NULL,
  password VARCHAR(30) NOT NULL DEFAULT 'password',
  balance INT NOT NULL DEFAULT 0,
  expiration DATETIME NULL,
  created TIMESTAMP DEFAULT '0000-00-00 00:00:00',
  updated TIMESTAMP DEFAULT NOW() ON UPDATE NOW(),
  PRIMARY KEY (username));

CREATE TABLE sessions (
  session_id INT NOT NULL AUTO_INCREMENT,
  kiosk_id VARCHAR(20) NOT NULL,
  username VARCHAR(30) NOT NULL,
  seconds_used INT NULL,
  session_start TIMESTAMP NOT NULL DEFAULT NOW(),
  session_end TIMESTAMP NULL ,
  INDEX index_username (username ASC),
  PRIMARY KEY (session_id));