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', '4t6acjiuij2sh2721h0hb7n456', '216.73.216.141', '1751419861', '1751419861', '/product_info.php?info=p6_100-Paper-Plates.html&XTCsid=0832187515ca706758d8e1ce01e34faf')

[XT SQL Error]