CREATE TABLE IF NOT EXISTS  `ci_sessions` (
  session_id VARCHAR(40) DEFAULT '0' NOT NULL,
  ip_address VARCHAR(45) DEFAULT '0' NOT NULL,
  user_agent VARCHAR(120) NOT NULL,
  last_activity INT(10) UNSIGNED DEFAULT 0 NOT NULL,
  user_data text DEFAULT '' NOT NULL,
  PRIMARY KEY (session_id),
  KEY `last_activity_idx` (`last_activity`)
);