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', '1dcm5qs2a9384fmes25tev15l7', '216.73.216.147', '1781022501', '1781022501', '/shop_content.php?XTCsid=4b76b23a7a255ffc6a8ec68c490ddaae&coID=2')

[XT SQL Error]