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', '0i54bfuhma3cg9nk803tt86s51', '107.22.127.78', '1493220805', '1493220805', '/shop_content.php?coID=1')

[XT SQL Error]