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', 'jt09igf44ejek8lo3ij6rk9ii0', '3.143.215.114', '1746769940', '1746769940', '/xtshop/index.php?cat=c10_.html')

[XT SQL Error]