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', 'slid6url80h19cc6svjegjfc02', '216.73.216.40', '1773601919', '1773601919', '/product_info.php?XTCsid=33509f1bee4ee2cbb673a74e5faae0d4&info=p17_20-Tissue-Napkins.html')

[XT SQL Error]