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', 'cofn0njukem571aa8hpu88itj7', '3.84.182.112', '1555936437', '1555936437', '/lkw_plane_tasche_lkw_plane/product_info.php/info/p140_Tasche-30-38-10-dunkelblau-hellblau-mit-Giraffe-in-hellblau.html')

[XT SQL Error]