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', 'dc7d9efbbd0f5c377b119c9a6cff751a', '216.73.216.169', '1755543578', '1755543578', '/shop/product_info.php?info=p123_.html')

[XT SQL Error]