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', 'o9kntl9vbc3bp1sjdcueg3nt37', '216.73.216.63', '1773685184', '1773685184', '/index.php')

[XT SQL Error]