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', 'cnjsa2ek7t4du1gm19hocjcfu1', '216.73.216.19', '1762994764', '1762994764', '/index.php?XTCsid=68406082ac8a7bd4f5ea97439380fef7')

[XT SQL Error]