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', 't6kpip7h8an2ii0corrovug784', '216.73.216.236', '1790227448', '1790227448', '/index.php?XTCsid=58a458a3fc8eed51d27848bcc8276a69')

[XT SQL Error]