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', 'n387qudm9fsbgm0ep1mmojch85', '216.73.216.167', '1762578791', '1762578791', '/shop_content.php?XTCsid=7c604026da355cfd6a094c68b431572d&coID=1')

[XT SQL Error]