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', '0ilkbgioq0tfres267d8lcmoc3', '216.73.216.244', '1752215465', '1752215465', '/shop_content.php?coID=2&XTCsid=274ec9b60c94b159bd8f2b261ed48387')

[XT SQL Error]