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', 'bortkdnfbk10p44k83lrrtjqc2', '216.73.216.244', '1752214948', '1752214948', '/shop_content.php?coID=8&XTCsid=85f438a686cbfb5e3ea5e5d6b9611958')

[XT SQL Error]