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', '57b2kdu9e4d2at40e8dlmng7g7', '216.73.216.63', '1774435429', '1774435429', '/index.php?XTCsid=8b393352c8b2119fa6bf5134aeccabe0')

[XT SQL Error]