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', 'fhbr3ltif91ejm2eg9adh23582', '216.73.216.113', '1775585892', '1775585892', '/product_info.php?XTCsid=792dd2eece839333bab562194e3fb545&info=p15_25-balloons.html')

[XT SQL Error]