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', 'kqf15jqgvo48m1flnto0dckib0', '216.73.216.140', '1789492775', '1789492775', '/shop_content.php?XTCsid=adc8c520bddaa9e02a40df1e2a90f128&coID=3')

[XT SQL Error]