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', '39o01thh13nqhe5odequhtruh4', '54.162.109.90', '1495803880', '1495803880', '/product_info.php?info=p1362_Edelstahl-Besteck-Set-16-tlg--rostfrei.html')

[XT SQL Error]