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', 'mb9m0vb6e3uj8d5rgig8gcu5r3', '216.73.216.197', '1751515153', '1751515153', '/product_info.php?info=p18_Fun-Hat.html&XTCsid=3dfedf8e10ab51b65faa7b7d7332d93a')

[XT SQL Error]