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', 'e4jklc9fl28r2grfifcdga21d5', '216.73.216.244', '1752211031', '1752211031', '/shop_content.php?coID=8&XTCsid=7f3d063595fd0cf7dd24ecea4b1409d6')

[XT SQL Error]