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', 'qb78n5ekbqjj6kchnns8tj9f24', '35.171.183.163', '1563243374', '1563243374', '/shop/index.php?cat=c77_Watkescher.html')

[XT SQL Error]