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', '9k41otokrhd4kv8i11rfvvn6j4', '216.73.217.120', '1793575872', '1793575872', '/shop_content.php?XTCsid=53b3ca17e11023a1f7ae6e1aa45a0ce7&coID=4')

[XT SQL Error]