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', 'ee3454bc4574a788d84ad202bf38aaa1', '54.198.246.164', '1563500195', '1563500195', '/shopping_cart.php')

[XT SQL Error]