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', 'ikja3tpssrqst2ugk8svg9at44', '216.73.216.180', '1766992822', '1766992822', '/product_info.php?XTCsid=3547ee950f9337e348e5e07def1466f0&info=p18_Fun-Hat.html')

[XT SQL Error]