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', '9167e3de7c5f59d22f0c2088178ffe1d', '216.73.216.42', '1763401254', '1763401254', '/shop/product_info.php?info=p123_.html')

[XT SQL Error]