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', 'h3q0lldiq69to6p2p1n2n4aop5', '216.73.216.147', '1751962412', '1751962412', '/index.php?language=de&XTCsid=38717c4dd62e88001622b2c7b8b8372a')

[XT SQL Error]