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', '5fas6i86pc2h35g4fldqho5dk5', '216.73.216.176', '1762434280', '1762434280', '/index.php?XTCsid=e65207aee44f142683bacdd3544c84a8&language=en')

[XT SQL Error]