1366 - Incorrect integer value: '' for column `mapshopatlogis`.`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', '539df81066218e5288e910569e1c4e00', '216.73.216.198', '1752878544', '1752878544', '/index.php/cat/c19_Reliefkarten-Digital.html?refID=1')

[XT SQL Error]