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', 'ehebh6lfpvr6gp5cioh9l3bu63', '216.73.216.122', '1767790800', '1767790800', '/shop_content.php?XTCsid=3547ee950f9337e348e5e07def1466f0&coID=8')

[XT SQL Error]