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', '8v7tt12ne2ur5tcgn4r1pp44f5', '3.147.75.50', '1746765468', '1746765468', '/xtshop/index.php?cat=c70_.html')

[XT SQL Error]