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', 'g7df50kj1c5eliqh534cm22983', '216.73.217.152', '1791178300', '1791178300', '/product_info.php?XTCsid=15cbbc13723f7bc63afaf1294f637517&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]