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', '0e4rerrkha2mes3lq7olvpflq7', '216.73.216.252', '1788918371', '1788918371', '/index.php?XTCsid=61ba925c46144fb6a3eaf868339da23b')

[XT SQL Error]