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', 'tnf068la35ucihi66atr8tc885', '3.85.92.139', '1561470048', '1561470048', '/shop_content.php/coID/10/product/Zu-DIR-oder-nach-MIR')

[XT SQL Error]