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', 'lme4t0ocanukv1546sj3fba4t4', '216.73.216.166', '1758167789', '1758167789', '/index.php?XTCsid=a79e5d61ec58bbc95717b82811d3becc')

[XT SQL Error]