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', '45192b15b70ded6430b40fe3efbfdf36', '216.73.216.213', '1767296818', '1767296818', '/shop/shopping_cart.php')

[XT SQL Error]