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', '27si85h5qrr09ihns9pem8fb82', '216.73.216.70', '1752612224', '1752612224', '/index.php?cat=c5_Crockery.html&XTCsid=adc8c520bddaa9e02a40df1e2a90f128')

[XT SQL Error]