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', 'ksf32ne78ab5ed4b4suc8a1s22', '216.73.216.145', '1778221436', '1778221436', '/shop_content.php?XTCsid=0832187515ca706758d8e1ce01e34faf&coID=3')

[XT SQL Error]