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', 'caibv6j3jfmkqq3e97j6n9a482', '216.73.216.165', '1752305097', '1752305097', '/product_info.php?language=de&info=p15_25-balloons.html&XTCsid=ec445a26a1be1b54e711876da9fff244')

[XT SQL Error]