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', 'kqhbh84k25lvkh285d8eleh846', '54.159.30.26', '1519131789', '1519131789', '/shop/')

[XT SQL Error]