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', 'er49mm2k0j7tg8pdllluepu6o1', '216.73.216.135', '1769738225', '1769738225', '/xtshop/product_info.php?info=p654_.html')

[XT SQL Error]