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', 'q43qob63apvebml4v57ito93r1', '216.73.216.118', '1761596524', '1761596524', '/product_info.php?XTCsid=80c3e9fc87b53cb0d288d19ef4e9b63c&info=p20_Paper-tablecloth-50-meters.html')

[XT SQL Error]