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', 'fuau1ht6ga556avbc459bcdqo2', '216.73.217.172', '1790564141', '1790564141', '/index.php?XTCsid=a3b8bf2959b629f4e700fd83d8e68631')

[XT SQL Error]