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', 't1k8e5gc9nm2lc7qudimrgad56', '18.97.14.85', '1754853603', '1754853603', '/xtshop/shop_content.php?coID=2')

[XT SQL Error]