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', 'isr5it216107irkn7gu81bcdk1', '216.73.216.170', '1762045990', '1762045990', '/product_info.php?XTCsid=a63f52844b6e675f480eaf86612536c2&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]