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', '7g6ast3rui5t3nul3m3j6lhqk3', '18.234.88.196', '1558465307', '1558465307', '/lkw_plane_tasche_lkw_plane/product_info.php/info/p119_Tasche-30-38-10-wei--braun-mit-Kreisen-in-orange---braun.html')

[XT SQL Error]