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', 'kv9mg4ffmgkhcdhhqvjjm61ih3', '216.73.216.199', '1780797582', '1780797582', '/index.php?XTCsid=734cd4ccfdd28635aaee5aea39e89c84')

[XT SQL Error]