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', '261b201df362337123a6c5d921e32581', '3.147.77.97', '1722085919', '1722085919', '/shop_content.php/coID/3/content/Unsere-AGB-s')

[XT SQL Error]