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', 'kg5t24p9ak6jesr4qdqkocijf2', '216.73.216.185', '1752883151', '1752883151', '/product_info.php?info=p11_Fan-for-decorations.html&XTCsid=28e6fbc3d253d01fbd676e85e6f35b1c')

[XT SQL Error]