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', '2t4u647vujmb7f6m3oqsfb2n94', '216.73.216.110', '1752972109', '1752972109', '/shop_content.php?coID=7&XTCsid=d3f81aac1b90a5822d8663a3af39931e')

[XT SQL Error]