1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', 'ugph4p892042kd0c2stu3tb4v7', '216.73.216.197', '1751515970', '1751515970', '/index.php?language=en&cat=c2_Decoration.html&XTCsid=f6e58886be8011b1d9a8e232c116cb7a')

[XT SQL Error]