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', '8af445fabe0cfccd6e29c153cc0fbf3b', '216.73.216.52', '1759535013', '1759535013', '/shop/product_info.php?info=p111_.html')

[XT SQL Error]