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', '221rdj2el9ir4odj0d6vdi1c17', '216.73.216.9', '1758222482', '1758222482', '/product_info.php?XTCsid=4299a8bbf7f56cb5a06703b866244eb3&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]