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', 'cl40mgiv4utg2s4p64m001c0d5', '216.73.216.244', '1752202256', '1752202256', '/index.php?XTCsid=37561e241660103b2a7d228c9129c96e')

[XT SQL Error]