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', 'l8jcfeavckivv2e48hhfm8sp52', '13.59.235.245', '1746768599', '1746768599', '/xtshop/index.php?cat=c17_.html')

[XT SQL Error]