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', 'tuk300p57udalcfp5go8jqgl91', '216.73.216.89', '1760831806', '1760831806', '/xtshop/product_info.php?info=p762_.html')

[XT SQL Error]