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', '6os5ufv0tv24rm32vbksfod517', '216.73.217.31', '1792166621', '1792166621', '/product_info.php?XTCsid=07630e5b15e9155d8246af3ee660ca0e&info=p22_Plastic-tablecloth.html')

[XT SQL Error]