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', '7f9bs7145l568icb5vja2a4025', '216.73.216.180', '1766247781', '1766247781', '/index.php?XTCsid=3ff39c1ecd10603727f45351a658e742')

[XT SQL Error]