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', '2j7f2i9f6m74hin24tlbblccr0', '216.73.216.9', '1757813406', '1757813406', '/shop_content.php?XTCsid=7c604026da355cfd6a094c68b431572d&coID=2')

[XT SQL Error]