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', 'j0m929rug4m64qibigbn5narn7', '216.73.216.9', '1758162497', '1758162497', '/index.php?XTCsid=d6a8bfd6f6ba5ba5c5448fc18660454f&cat=c4_Beer-Mugs.html')

[XT SQL Error]