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', 'al9ib7a1h02f2s07t2bpgppqo0', '216.73.216.165', '1752308160', '1752308160', '/product_info.php?language=de&info=p19_10-Paper-Plates.html&XTCsid=b4e317ab79f3ee4221fe0e84cc3a81a4')

[XT SQL Error]