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', '86ujj9sm321v9mcnig6c59e0n3', '216.73.216.165', '1752305421', '1752305421', '/shop_content.php?coID=7&XTCsid=3547ee950f9337e348e5e07def1466f0')

[XT SQL Error]