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', '6odhtb3stg01u5odeelnoov0d2', '216.73.216.180', '1766701396', '1766701396', '/shop_content.php?XTCsid=e990f3916c880610adc34c2fa7d30f83&coID=3')

[XT SQL Error]