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', 'cm654n5hl0s30iqvabgennr0u5', '216.73.216.113', '1752883988', '1752883988', '/product_info.php?info=p2_Bavarian-Pennant-Chain.html&XTCsid=38717c4dd62e88001622b2c7b8b8372a')

[XT SQL Error]