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', '3fq0h0jlj19tkcugs0q3uo8n11', '18.232.53.231', '1566528857', '1566528857', '/Kontakt:_:7.html')

[XT SQL Error]