$this->db->query($sql);Fires a database query, the SQL code can be input between the brackets as normal.
$this->db->escape($value);Escapes potentially harmful characters from posted data before entering them into the database. Useful for avoiding SQL injection attacks.
$this->db->countAffected();Returns the number of affected rows after a query string.
$this->db->getLastId();Get the last inserted ID number for a database.