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', 'qorkkl4htgegffr7fd82smgr22', '216.73.216.165', '1752307595', '1752307595', '/popup_content.php?coID=1&XTCsid=d0fb6f95a363340d124d7dc76e615e44')

[XT SQL Error]