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', '69a42196a99c42f3e80412232837d9e1', '216.73.216.42', '1763354864', '1763354864', '/shop/product_info.php?info=p64_.html')

[XT SQL Error]