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', '7vs3qsfcsvjjka8pradar9mqf7', '216.73.216.122', '1767866388', '1767866388', '/popup_content.php?XTCsid=33509f1bee4ee2cbb673a74e5faae0d4&coID=1')

[XT SQL Error]