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', 'ebor9gbjd9rrfs0f139dit4o76', '216.73.216.4', '1771281027', '1771281027', '/index.php?XTCsid=68406082ac8a7bd4f5ea97439380fef7')

[XT SQL Error]