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', '25m1gsqclr0smquv8i06dafl41', '216.73.217.152', '1791032439', '1791032439', '/product_info.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&info=p16_Octoberfest-CD.html')

[XT SQL Error]