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', '2qrs5igst5fr64lkcncchh4bq3', '216.73.216.9', '1758070694', '1758070694', '/product_info.php?XTCsid=1455d70b156c4853db961f68b595bbe7&info=p13_Deco-ball.html')

[XT SQL Error]