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', 'j9p3affpudhhl8lt1aslt1o2s1', '216.73.216.147', '1751962453', '1751962453', '/index.php?cat=c11_Room-decorations.html&XTCsid=3f98699a7205aa16d7f8014dc7c0d34a')

[XT SQL Error]