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', 'e41eaa2981901dc4aab24dcdd3c87667', '34.229.24.100', '1563485330', '1563485330', '/password_double_opt.php/language/de')

[XT SQL Error]