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', 'd1bic0ud1llg7hrrd5fu4v0a33', '216.73.216.110', '1752055720', '1752055720', '/index.php?cat=c4_Beer-Mugs.html&XTCsid=38f09672db884903e3803adf9d076819')

[XT SQL Error]