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', 't78622v8psl7qemcksj9usd340', '216.73.216.9', '1757936305', '1757936305', '/product_info.php?XTCsid=4299a8bbf7f56cb5a06703b866244eb3&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]