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', '4g28nig70t4bih9svom3gfmrg0', '216.73.216.113', '1752883869', '1752883869', '/shop_content.php?coID=2&XTCsid=ec445a26a1be1b54e711876da9fff244')

[XT SQL Error]