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', 'e8a186a4f37d2e6d1205cccf57ad25a0', '216.73.216.213', '1767340655', '1767340655', '/shop/product_info.php?info=p133_.html')

[XT SQL Error]