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', 'qg9vkv84f1a0gcjbp4g6mgo5o1', '216.73.216.187', '1773426847', '1773426847', '/index.php?XTCsid=53b3ca17e11023a1f7ae6e1aa45a0ce7&cat=c8_Disposable-tableware.html')

[XT SQL Error]