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', 'p32b40ufm3np7igkme858k6hq5', '216.73.216.244', '1752216625', '1752216625', '/shop_content.php?coID=4&XTCsid=98fab66f7c5bcfa7f4c82f0bdb1cf869')

[XT SQL Error]