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', 'ehst1eeb617i7dip35iefia580', '216.73.216.40', '1773593142', '1773593142', '/shop_content.php?XTCsid=cdfc0f2ea8be6cebe1f6056b0a37d83f&coID=2')

[XT SQL Error]