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', '5mo1feqo7naghtb3g5au6fqp53', '18.191.28.190', '1746791209', '1746791209', '/xtshop/index.php?cat=c102_.html')

[XT SQL Error]