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', 'ukp4k7eni57nau4vljg3mgd1t7', '216.73.216.122', '1767877825', '1767877825', '/shop_content.php?XTCsid=98fab66f7c5bcfa7f4c82f0bdb1cf869&coID=2')

[XT SQL Error]