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', 's9f8kjthm99756cqtf2hqcnrj0', '216.73.216.180', '1767179792', '1767179792', '/index.php?XTCsid=68d3e27ea16f220cd89842c811d00725')

[XT SQL Error]