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', 'dq3cudpqv4dqn8qfftt89atev0', '216.73.216.110', '1752052095', '1752052095', '/product_info.php?info=p22_Plastic-tablecloth.html&XTCsid=28e6fbc3d253d01fbd676e85e6f35b1c')

[XT SQL Error]