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', 'a1q048ljnr5avjp90ghasug105', '216.73.216.244', '1752213604', '1752213604', '/shop_content.php?coID=1&XTCsid=1455d70b156c4853db961f68b595bbe7')

[XT SQL Error]