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', 'ph9h19v730vl1qmd2k93gta6s0', '13.59.144.10', '1746764801', '1746764801', '/xtshop/index.php?cat=c77_.html')

[XT SQL Error]