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', 'b384fdf6b9a1aa0fd3efba2f4d28359b', '216.73.216.42', '1763440894', '1763440894', '/shop/index.php?cPath=9_6_24')

[XT SQL Error]