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', '04a70427dcd3773d04c18bdeb4e7df98', '216.73.216.186', '1770811623', '1770811623', '/shop/index.php')

[XT SQL Error]