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', '3in432jlg2rv2spe12vsqjqs84', '216.73.216.9', '1758172093', '1758172093', '/index.php?XTCsid=3dfedf8e10ab51b65faa7b7d7332d93a&cat=c12_Music.html')

[XT SQL Error]