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', 'kh91lr7l9kdjk028b6nin8rks4', '3.143.24.174', '1746767908', '1746767908', '/xtshop/index.php?cat=c24_.html')

[XT SQL Error]