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', '5cenh0bf9al0u75aea9k6frng2', '216.73.216.197', '1751518586', '1751518586', '/index.php?cat=c5_Crockery.html&XTCsid=9265b55633a2cb4e8ed6db3536c73ca5')

[XT SQL Error]