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', 'bskv7e2078afrcvmq27ugvh113', '216.73.217.152', '1791194348', '1791194348', '/shop_content.php?XTCsid=a63f52844b6e675f480eaf86612536c2&coID=7')

[XT SQL Error]