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', 'grq6uoo3km9997gd0ksq1vka91', '3.17.176.160', '1746962615', '1746962615', '/xtshop/product_info.php?info=p882_.html')

[XT SQL Error]