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', 'v75udfedc483adceq12m5hiqp4', '216.73.216.9', '1757991234', '1757991234', '/index.php?XTCsid=32bc53310efafffaa756fafd3e8b8712')

[XT SQL Error]