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', 'rgca38es2ts97qi6q4p2neaud6', '216.73.216.127', '1752881658', '1752881658', '/index.php?XTCsid=ca2ccb31e09c93d2f0161ae2045ab92c')

[XT SQL Error]