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', '5sg4hh704mpunh69tr15iu5ta5', '216.73.216.185', '1752883344', '1752883344', '/shop_content.php?coID=2&XTCsid=a61b1c7c4e21580bd9d4e85a32d692bc')

[XT SQL Error]