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', '4jdo6s809btfkacdqmi82u7s83', '216.73.216.180', '1767228974', '1767228974', '/shop_content.php?XTCsid=5452c15f57f0ea9ce022f9dc9cfaa045&coID=3')

[XT SQL Error]