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', 'cti7ih2q94jbgkrj7k0pclc1k5', '107.22.127.78', '1493220923', '1493220923', '/product_info.php?info=p242_Mueslibox--Todflakes-.html&cat=c83_Dosen.html')

[XT SQL Error]