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', 'sdavjfoan89gh24r239n9tts64', '216.73.216.60', '1760425628', '1760425628', '/product_info.php?XTCsid=07630e5b15e9155d8246af3ee660ca0e&info=p2_Bavarian-Pennant-Chain.html&language=de')

[XT SQL Error]