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', 'epf251mquckp71q5l58buqneo4', '216.73.216.185', '1752883523', '1752883523', '/product_info.php?info=p11_Fan-for-decorations.html&XTCsid=c407ede434192d8d024c7c2f06b2be8c')

[XT SQL Error]