1366 - Incorrect integer value: '' for column `liembergerphp`.`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', 'l0t7ot1vfue02fgg4hq3fjabq5', '18.212.222.217', '1550525136', '1550525136', '/~liembergerphp/xtcommerce/index.php')

[XT SQL Error]