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', 's4h4esj74pdkpp8b9bl6orfk77', '216.73.216.114', '1789009362', '1789009362', '/index.php?XTCsid=950ffb10fb43fc07eb6836be05601b5f')

[XT SQL Error]