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', 'alitffb4hnqat5qsv5di4m6tf1', '216.73.216.147', '1751839566', '1751839566', '/shop_content.php?coID=3&XTCsid=1ce6d0a6925740e42ccf6986944a240a')

[XT SQL Error]