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', '2jfoco18hmgrl0um33jhot3ll1', '216.73.216.113', '1775395888', '1775395888', '/shop_content.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&coID=8')

[XT SQL Error]