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', 'um44knb388jfc6fbhto0ckivk7', '216.73.216.147', '1751839065', '1751839065', '/index.php?cat=c5_Crockery.html&XTCsid=67a1ee4a966bad4e2954e4e321814afb')

[XT SQL Error]