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', '3n0vl5b0pstuvnou7oss2cdk71', '216.73.216.127', '1752882021', '1752882021', '/index.php?cat=c5_Crockery.html&XTCsid=67a1ee4a966bad4e2954e4e321814afb')

[XT SQL Error]