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', 'q0e8s9c3miu35pl48jf1vo9lo3', '216.73.216.7', '1758254747', '1758254747', '/product_info.php?XTCsid=159458ffcd70853368c82c29206c1527&info=p14_65-drinking-cups-1-2-Liter.html')

[XT SQL Error]