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', 'd0hldrm9vu04gb05a7op6d9du4', '216.73.216.9', '1758143104', '1758143104', '/product_info.php?XTCsid=1ce6d0a6925740e42ccf6986944a240a&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]