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', 'kklsflf50prp5csf35uhgtpqc5', '216.73.216.63', '1773907061', '1773907061', '/shop_content.php?XTCsid=d0fb6f95a363340d124d7dc76e615e44&coID=7')

[XT SQL Error]