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', 'n6gvtp2h5lak54v69mvdl08co2', '216.73.216.9', '1757977583', '1757977583', '/index.php?XTCsid=0223be5c598016f9e4ed4c9b01f33ea6')

[XT SQL Error]