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', '5lo1q4l1fnhkem7d9r2u8bdis7', '216.73.216.82', '1752529208', '1752529208', '/index.php?XTCsid=29fd12a64896f56c53d4fbec2ed56081')

[XT SQL Error]