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', 'ss8oi1ltn3nt58l3752jha1fu7', '216.73.216.87', '1785926341', '1785926341', '/index.php?XTCsid=38f09672db884903e3803adf9d076819&cat=c12_Music.html')

[XT SQL Error]