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', '0gar0n9ipiglkvf2vg46akrlo6', '216.73.217.172', '1790560207', '1790560207', '/shop_content.php?XTCsid=0832187515ca706758d8e1ce01e34faf&coID=4')

[XT SQL Error]