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', '7r49l5hearc38pk07k51a3alm0', '216.73.216.122', '1761711284', '1761711284', '/xtshop/product_info.php?info=p834_.html')

[XT SQL Error]