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', '1fpmlbnhm5t6a2nvdtvlp2emj1', '216.73.216.110', '1752058867', '1752058867', '/index.php?cat=c5_Geschirr.html&XTCsid=ec445a26a1be1b54e711876da9fff244')

[XT SQL Error]