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', 'l03o8q9s6ufv0b7kh898h78in6', '216.73.216.31', '1774961979', '1774961979', '/index.php?XTCsid=68d3e27ea16f220cd89842c811d00725')

[XT SQL Error]