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', 'if1oabrc1vjlk41e735srvtin3', '216.73.216.141', '1751424785', '1751424785', '/product_info.php?info=p18_Spa--Hut.html&XTCsid=ec445a26a1be1b54e711876da9fff244')

[XT SQL Error]