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', '5hbfkc3npv8dda4fmhtaa05ee7', '52.14.244.213', '1746766198', '1746766198', '/xtshop/index.php?cat=c73_.html')

[XT SQL Error]