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', 'bm5lnor9bncoegvh0okrutmmo7', '216.73.217.152', '1791019140', '1791019140', '/product_info.php?XTCsid=363052f8eb28c495db1ddeca225278d6&info=p15_25-balloons.html')

[XT SQL Error]