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', 'kr4ahg55p190vavh3jjk83bb33', '216.73.216.70', '1752612171', '1752612171', '/product_info.php?info=p21_Paper-tablecloth-10-meters.html&XTCsid=2f0d32e80e0e3a7e9efdd2dc2a571c8d')

[XT SQL Error]