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', '3pt9004vb3gdqrt3llc4lkl156', '216.73.216.80', '1751314719', '1751314719', '/index.php?XTCsid=6171a6cc3e0307bdedccefb9794f2e2c')

[XT SQL Error]