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', 'b1its6oqm9la5d7814215d6i31', '216.73.216.244', '1752213461', '1752213461', '/shop_content.php?coID=3&XTCsid=d6a8bfd6f6ba5ba5c5448fc18660454f')

[XT SQL Error]