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', '8slv9popq4i6a1nl3o06edcov2', '216.73.216.180', '1766174497', '1766174497', '/product_info.php?XTCsid=ec445a26a1be1b54e711876da9fff244&info=p17_20-Servietten.html')

[XT SQL Error]