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', '25ca6f8a467e0c1a1fe52c467c35094d', '54.234.136.147', '1711670853', '1711670853', '/redirect.php?action=product&id=73')

[XT SQL Error]