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', '1f5d318394b3574d1f9e37bdd09765cb', '216.73.216.219', '1772242127', '1772242127', '/shop/newsletter.php')

[XT SQL Error]