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', 'th0tf9ljkft1g67b1qjqln5en5', '216.73.216.63', '1774212732', '1774212732', '/product_info.php?XTCsid=38f09672db884903e3803adf9d076819&info=p11_Fan-for-decorations.html')

[XT SQL Error]