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', '4s0pi1rp6gr5d4iuok82ine8o2', '216.73.216.9', '1758215813', '1758215813', '/index.php?XTCsid=15cbbc13723f7bc63afaf1294f637517&cat=c4_Beer-Mugs.html')

[XT SQL Error]