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', 'prf0m47u209khtf9aefacbr4g2', '216.73.216.185', '1752883489', '1752883489', '/index.php?XTCsid=78d104da211603518fe01de887166f28')

[XT SQL Error]