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', '1tq9bobt910k6oj1801d7c1f47', '3.148.217.26', '1746768548', '1746768548', '/xtshop/shop_content.php?coID=4')

[XT SQL Error]