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', '1bkvp2d3u0fmt05ur8e3qfvp07', '216.73.216.7', '1758259606', '1758259606', '/index.php?XTCsid=cc2df0871f5f3d52a88b086fc6d31ad8')

[XT SQL Error]