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', '8a71a03bb79bb6a34dc0dca36da449c9', '34.229.24.100', '1563484575', '1563484575', '/shop_content.php/coID/2/content/Privatsphaere-und-Datenschutz')

[XT SQL Error]