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', 'jsg87et0a3l4d13gkb5edgpdo0', '216.73.216.113', '1752884488', '1752884488', '/product_info.php?info=p21_Paper-tablecloth-10-meters.html&XTCsid=15cbbc13723f7bc63afaf1294f637517')

[XT SQL Error]