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', 'nm73jei3kkvaaauqba9lr2p463', '216.73.216.7', '1758227477', '1758227477', '/product_info.php?XTCsid=38f09672db884903e3803adf9d076819&info=p15_25-balloons.html')

[XT SQL Error]