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', '4vjjem1tv09u7h15h6mchvm3o3', '54.224.247.75', '1498404305', '1498404305', '/')

[XT SQL Error]