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', '4gohbogtfk8kpeuu9s1s47mfs2', '216.73.216.244', '1752218333', '1752218333', '/product_info.php?info=p15_25-balloons.html&XTCsid=b4e317ab79f3ee4221fe0e84cc3a81a4')

[XT SQL Error]