Problem in db session

[eluser]Unknown[/eluser]
Hi,

I have a problem in using db session

Error displayed the time of login

A Database Error Occurred

Error Number: 1054

Unknown column 'user_data' in 'field list'

UPDATE `ci_sessions` SET `last_activity` = 1332915226, `user_data` = 'a:1:{s:15:\"session_user_id\";s:2:\"92\";}' WHERE `session_id` = '4ca4c9c613dfdd26256c4b0ace08a3e8'

I m using the database like this

CREATE TABLE IF NOT EXISTS `ci_sessions` (
session_id varchar(40) DEFAULT '0' NOT NULL,
ip_address varchar(16) DEFAULT '0' NOT NULL,
user_agent varchar(50) NOT NULL,
last_activity int(10) unsigned DEFAULT 0 NOT NULL,
session_data text default '' not null,
PRIMARY KEY (session_id)
);

Here no field named user_data in the above table but the error message shows unknown column user_data

We need any change in the ci_sessions table?

Please help