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', 'bjm8aibgj4lhshtt9uqskkrhh4', '216.73.216.9', '1758199812', '1758199812', '/shop_content.php?XTCsid=38f09672db884903e3803adf9d076819&coID=3')

[XT SQL Error]