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', 'mrsvib0fkasbu1uqt83du60je5', '35.172.100.232', '1569201237', '1569201237', '/shop_content.php/coID/8/product/Sitemap')

[XT SQL Error]