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', 'aed734a8177572e8d5991e869f916049', '3.22.79.125', '1722054999', '1722054999', '/product_info.php/info/p66_MET-Honigwein-0-75-l--de-Immenwaechter--lieblich-aus-Bluetenhonig.html')

[XT SQL Error]