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', 'u4mi58ct3j4gf7qag15gn6oa11', '34.204.173.36', '1574186484', '1574186484', '/shop/index.php')

[XT SQL Error]