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', '033k5fu6456ib9h8uii1pcuho6', '216.73.216.63', '1774150719', '1774150719', '/product_info.php?XTCsid=81fba26e1f006e30d12d9ee4d58a4030&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]