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', 'l1f396cjd1g0pnv70h5ar90sp1', '54.162.109.90', '1495803980', '1495803980', '/product_info.php?info=p154_Cartoon-Tasse.html&cartoon=864')

[XT SQL Error]