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', 'kuqtj245kbvl6f5m1hc33qphv0', '216.73.216.122', '1767785651', '1767785651', '/index.php?XTCsid=0920dd1f7934388b33528580c92ca640&cat=c6_Foodstuffs.html')

[XT SQL Error]