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', 't48lrb7rob6choa1atfnei8r67', '216.73.216.165', '1752395909', '1752395909', '/index.php?XTCsid=3927d66f1162df83a1f40750d6538238')

[XT SQL Error]