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', '0qinl2vlo2ulnc3mpsvg6ht837', '216.73.217.78', '1791217037', '1791217037', '/index.php?XTCsid=7721da20a623cbf55c11923452088e5a')

[XT SQL Error]