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', 'hmrutj7smu19qptu5mi12sou94', '216.73.216.40', '1773587322', '1773587322', '/shop_content.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&coID=7')

[XT SQL Error]