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', 'mv3b4va8rrd00h6678jh624sf2', '216.73.216.31', '1774987182', '1774987182', '/index.php?XTCsid=38f09672db884903e3803adf9d076819&cat=c5_Crockery.html')

[XT SQL Error]