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', 'e5c57f1c607332d727426a14dcf7500a', '216.73.217.165', '1780981129', '1780981129', '/shop/product_info.php?info=p141_.html')

[XT SQL Error]