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', '932gq9vc0qochbvqr9j1nb3kl1', '216.73.217.152', '1791075921', '1791075921', '/index.php?XTCsid=ec445a26a1be1b54e711876da9fff244&cat=c8_Einweggeschirr.html')

[XT SQL Error]