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', 'seqr5klpibhtm960h2n0gvs583', '216.73.216.147', '1751745808', '1751745808', '/index.php?cat=c4_Beer-Mugs.html&XTCsid=d6a8bfd6f6ba5ba5c5448fc18660454f')

[XT SQL Error]