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', 't2vd6atb270i3n6eop1588d8e0', '216.73.216.180', '1766085838', '1766085838', '/index.php?XTCsid=1455d70b156c4853db961f68b595bbe7&cat=c12_Music.html')

[XT SQL Error]