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', 't2h72a1p0fkjjb2sn5e6pcu4f6', '216.73.216.70', '1752613253', '1752613253', '/index.php?cat=c13_Accessoires.html&XTCsid=3f98699a7205aa16d7f8014dc7c0d34a')

[XT SQL Error]