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', 'p90clg3fgcoa5518544um9qfm0', '216.73.216.9', '1758178952', '1758178952', '/product_info.php?XTCsid=81fba26e1f006e30d12d9ee4d58a4030&info=p13_Deco-ball.html')

[XT SQL Error]