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', '170ki54q0vo2r6r0jpcccjvgm7', '216.73.216.121', '1761810051', '1761810051', '/product_info.php?XTCsid=a61b1c7c4e21580bd9d4e85a32d692bc&info=p15_25-balloons.html')

[XT SQL Error]