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', 'cja0okl4g6e9hrd0ut9ap0m1h1', '216.73.216.155', '1767607444', '1767607444', '/product_info.php?XTCsid=c407ede434192d8d024c7c2f06b2be8c&info=p17_20-Tissue-Napkins.html')

[XT SQL Error]