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', '561v6sp4upluvveb5hfq2s86c0', '216.73.216.147', '1751964085', '1751964085', '/product_info.php?info=p8_100-Placemats.html&XTCsid=1455d70b156c4853db961f68b595bbe7')

[XT SQL Error]