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', 'b599f514016fccd3a21d790b4d5e147f', '216.73.217.165', '1780981216', '1780981216', '/shop/index.php?XTCsid=041c8fc0413f2441df67fe52a6815a15&cPath=1')

[XT SQL Error]