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', '09e8270064ffc67fba2c59b4ac442aea', '216.73.217.33', '1782505890', '1782505890', '/shop/index.php')

[XT SQL Error]