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', '98lq4aq16p68oe1u55o1ntcce4', '216.73.216.130', '1760771120', '1760771120', '/product_info.php?XTCsid=28e6fbc3d253d01fbd676e85e6f35b1c&info=p22_Plastic-tablecloth.html')

[XT SQL Error]