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', '3o8msrcledsph4vl612pe1u9c3', '216.73.216.113', '1775190728', '1775190728', '/index.php?XTCsid=d6a8bfd6f6ba5ba5c5448fc18660454f&cat=c13_Accessoires.html')

[XT SQL Error]