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', '627pjt6l6umr0rdprjne7codc0', '216.73.216.118', '1761580981', '1761580981', '/product_info.php?XTCsid=adc8c520bddaa9e02a40df1e2a90f128&info=p12_33-feet-crape-paper.html')

[XT SQL Error]