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', 'qbk8v7ugfdgsvhhdpa95re9do7', '216.73.216.9', '1758140556', '1758140556', '/index.php?XTCsid=fe17aeeb335451fe173980da2ac8cb0a')

[XT SQL Error]