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', 'c3sr66na6587agnen9tqfsass2', '54.235.4.196', '1555920408', '1555920408', '/')

[XT SQL Error]