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', '1gfrfql9flcpobhgs5jsgombc3', '216.73.216.118', '1761379061', '1761379061', '/index.php?XTCsid=fe17aeeb335451fe173980da2ac8cb0a')

[XT SQL Error]