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', 'f2570e04974d4e9053a9b41e25c2c807', '216.73.216.42', '1763383942', '1763383942', '/shop/product_info.php?info=p154_.html')

[XT SQL Error]