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', 'llif1s8jg421912jc57pb95037', '18.219.68.172', '1746980027', '1746980027', '/xtshop/product_info.php?info=p994_.html')

[XT SQL Error]