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', 'vbud52n6ag1onfmn7p5f2ddj95', '54.161.128.52', '1481436208', '1481436208', '/')

[XT SQL Error]