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', 'bkgfnh82tqvevjfred2p2c6hg4', '18.97.14.80', '1773467128', '1773467128', '/xtshop/product_info.php?info=p400_.html')

[XT SQL Error]