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', 'lnanf9f2tgn50s4gcv4it0dhk3', '216.73.216.82', '1752528220', '1752528220', '/product_info.php?info=p2_Bavarian-Pennant-Chain.html&XTCsid=0832187515ca706758d8e1ce01e34faf')

[XT SQL Error]