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', '303mvvm3gs8kl18ngliqh2amo2', '216.73.216.141', '1751416984', '1751416984', '/product_info.php?info=p7_Garland-13-feet.html&XTCsid=2f0d32e80e0e3a7e9efdd2dc2a571c8d')

[XT SQL Error]