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', '0qqrdrn1676i03tdt4l292oms0', '216.73.216.208', '1788645660', '1788645660', '/product_info.php?XTCsid=75dc59d6a30660e0992222d2318ca53e&info=p17_20-Tissue-Napkins.html')

[XT SQL Error]