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', '4ca3e4948dde81525fdf77bce940a207', '34.229.24.100', '1563484504', '1563484504', '/shop_content.php/coID/7/content/Kontakt')

[XT SQL Error]