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', '8o3jj63r7itm4aic1r1srgd206', '3.133.87.185', '1746766564', '1746766564', '/xtshop/index.php?cat=c6_.html')

[XT SQL Error]