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', '5m2tlq99i5ap529aof15bdsmg5', '216.73.216.187', '1773383549', '1773383549', '/product_info.php?XTCsid=a8f768c639dfd62c2d6d3cd7ed21b720&info=p12_33-feet-crape-paper.html')

[XT SQL Error]