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', 'iar9qufngluj7o9q3bq8o7pa25', '216.73.216.144', '1781890451', '1781890451', '/xtshop/product_info.php?info=p1040_.html')

[XT SQL Error]