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', '3vbngc0j35avc60umjvn93jjh0', '216.73.217.15', '1792041465', '1792041465', '/product_info.php?XTCsid=ca28ab8f46bb6e791b42fe9b92719761&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]