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', 'v28cr5n87vd1pprdaie43744n2', '216.73.216.70', '1752610431', '1752610431', '/product_info.php?info=p18_Fun-Hat.html&XTCsid=d0fb6f95a363340d124d7dc76e615e44')

[XT SQL Error]