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', '9oo5s27vlspejjh7cfc3i0ujh1', '216.73.217.152', '1791019725', '1791019725', '/product_info.php?XTCsid=3f98699a7205aa16d7f8014dc7c0d34a&info=p18_Fun-Hat.html')

[XT SQL Error]