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', '4e6b54301882b9773c3016355ecc44ca', '216.73.217.165', '1780980755', '1780980755', '/shop/product_info.php?info=p145_.html')

[XT SQL Error]