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', 'jab123s0h44n1qep80ji71u8i2', '216.73.216.139', '1770241960', '1770241960', '/shop_content.php?XTCsid=d0fb6f95a363340d124d7dc76e615e44&coID=4')

[XT SQL Error]