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', '9euvu72n9oopj1pc3v3b9poah4', '216.73.216.118', '1761564426', '1761564426', '/index.php?XTCsid=4a36e01ba0c3a9f980ba4feccbdc4c93')

[XT SQL Error]