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', '7fhbmeo91ou4ubbe8cqfmbson0', '216.73.216.9', '1757923431', '1757923431', '/product_info.php?XTCsid=502c4d4f7753d1888d9a6ca985d5c9c9&info=p21_Paper-tablecloth-10-meters.html')

[XT SQL Error]