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', 'cegvo2i6564uo4p2808biaib02', '216.73.216.9', '1758177018', '1758177018', '/shop_content.php?XTCsid=c91bf92f8d99bec960c8de2e525c5ab4&coID=1')

[XT SQL Error]