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', '8psl6it9m8sajrbqg1t57sqjl4', '216.73.216.99', '1761919810', '1761919810', '/index.php?XTCsid=a62bc14a2472a2e20215fc39a8dcda1a')

[XT SQL Error]