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', '63leklqij9o70nfqt1j5ecst55', '216.73.216.60', '1760371746', '1760371746', '/product_info.php?XTCsid=81fba26e1f006e30d12d9ee4d58a4030&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]