1366 - Incorrect integer value: '' for column `hbl_shop`.`whos_online`.`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', 'fgf4rjnf71uuq8difeateng9i7', '216.73.216.47', '1758190996', '1758190996', '/product_info.php?info=p536_405748-Pfostentraeger-Dorn-zum-Einbetonieren--hoehenverstellbar-80.html')

[XT SQL Error]