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', 'iph58n9mpc9ehq03omui0hbt76', '216.73.216.9', '1757973761', '1757973761', '/product_info.php?XTCsid=7c604026da355cfd6a094c68b431572d&info=p16_Octoberfest-CD.html')

[XT SQL Error]