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', 'rc1h0n7p2hht7m7cgojq3a1i90', '216.73.216.70', '1752610380', '1752610380', '/index.php?cat=c5_Crockery.html&XTCsid=7c604026da355cfd6a094c68b431572d')

[XT SQL Error]