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', 'fu1ltcsnf6jmrhchhcj63rr240', '216.73.216.80', '1751321483', '1751321483', '/product_info.php?info=p17_20-Tissue-Napkins.html&XTCsid=1455d70b156c4853db961f68b595bbe7')

[XT SQL Error]