Userlib - User Library

[eluser]Unknown[/eluser]
How about column 'user_data' in the 'ci_sessions' table?

The next error occurs when I type right login and password. In other case I see "0".

Code:

if( $this->userlib->login( $_POST['login'], $_POST['password'] ) )
      {
          echo "1";
      }
      else
      {
          echo "0";    
      }

A Database Error Occurred
Error Number: 1054

Unknown column 'user_data' in 'field list'

UPDATE `ci_sessions` SET `last_activity` = '1227724828', `user_data` = 'a:2:{s:8:\"username\";s:8:\"user1310\";s:8:\"password\";s:40:\"84e3ac481dd7e5360cad7225a232fffb2c94d64a\";}' WHERE `session_id` = '790c74a9c6a13cdea3a7c8d7e1327750'

When I add column 'user_data' in the 'ci_sessions' table everything is OK.
Why the author didn't write about this or may be I do something wrong?