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', 'li9jsalu2foaek19c7t2r3lt34', '216.73.216.87', '1765819770', '1765819770', '/product_info.php?XTCsid=cdfc0f2ea8be6cebe1f6056b0a37d83f&info=p2_Bavarian-Pennant-Chain.html')

[XT SQL Error]