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', '4pctlr02la1bsrob12v1p4duf1', '216.73.217.147', '1778028906', '1778028906', '/product_info.php?XTCsid=38f09672db884903e3803adf9d076819&info=p16_Octoberfest-CD.html')

[XT SQL Error]