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', 'ccbonk46tuh0m862mv6nt699c5', '216.73.216.80', '1751320951', '1751320951', '/product_info.php?info=p20_Paper-tablecloth-50-meters.html&XTCsid=0832187515ca706758d8e1ce01e34faf')

[XT SQL Error]