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', 'nsmdkjtp1flg6sqlrev7kh40v3', '216.73.216.80', '1751314665', '1751314665', '/index.php?cat=c6_Foodstuffs.html&XTCsid=3f98699a7205aa16d7f8014dc7c0d34a')

[XT SQL Error]