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', 'b2f23a7a3ee1c306d9f36e18baba232f', '216.73.216.132', '1759445437', '1759445437', '/shop/newsletter.php')

[XT SQL Error]