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', '26e7b837b4e628f3da897bc123fdb761', '54.204.117.206', '1711709899', '1711709899', '/shopping_cart.php')

[XT SQL Error]