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', 'ku0sa9q24k7b9r6clj5sr3n380', '216.73.217.126', '1787851950', '1787851950', '/xtshop/product_info.php?info=p1045_.html')

[XT SQL Error]