1366 - Incorrect integer value: '' for column `hollen`.`whos_online`.`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, http_referer) values ('', 'Guest', '2ghlg7oi0nfh9e0k02vfvbt0h7', '34.204.202.44', '1586468331', '1586468331', '/popup_content.php?coID=1&KeepThis=true&TB_iframe=true&height=400&width=600', 'Keiner/None')

[XT SQL Error]