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', 'rlinq71d1q76ah2isq3429e215', '216.73.216.7', '1758256823', '1758256823', '/product_info.php?XTCsid=b4e317ab79f3ee4221fe0e84cc3a81a4&info=p15_25-balloons.html')

[XT SQL Error]