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', 'c1e3cpa5u4gpp2gejsug3eg450', '216.73.217.129', '1779138506', '1779138506', '/index.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32&cat=c5_Crockery.html')

[XT SQL Error]