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', 's4cub7b74cnp0fmoqoi7qrrf21', '216.73.216.60', '1760406907', '1760406907', '/index.php?XTCsid=f6e58886be8011b1d9a8e232c116cb7a&cat=c9_Tabledeko.html')

[XT SQL Error]