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', '6rbuq519bclo2jehrcn4mc1ck3', '216.73.216.87', '1765588660', '1765588660', '/index.php?XTCsid=0f3ad1dd1ca5779d4e10550142002046')

[XT SQL Error]