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', '2g75ecjohrsvte0itv3arqhi65', '216.73.217.172', '1790470643', '1790470643', '/index.php?XTCsid=54fe90272f17578d553875e28583f966')

[XT SQL Error]