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', '4o35hnlsdfhm3qab0b05eq6qv6', '34.229.76.193', '1558617396', '1558617396', '/Kontakt:_:7.html')

[XT SQL Error]