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', '5p6tp57bv09etlvob1ppmh64v7', '216.73.216.110', '1752044340', '1752044340', '/product_info.php?info=p21_Paper-tablecloth-10-meters.html&XTCsid=81fba26e1f006e30d12d9ee4d58a4030')

[XT SQL Error]